Discovery
,In the first installment of „The Genome Wardrobe,” Elizabeth I’s dress in the Ditchley Portrait encoded cholera toxin (PDB: 1XTC). In the second, a gold dress from The Cabildo concealed the HPV pentamer (PDB: 8YEF). In the third, the „Pouf à l’Asiatique” hairstyle from a fashion catalogue turned out to be the AMPA receptor (PDB: 6RUQ). In the fourth, the „Top and Tail” caricature hid the TRPC3 ion channel (PDB: 9U5C, 5ZBG).
This time, not a dress. Not a hairstyle. Not a caricature. Underwear.
The title image shows an 18th-century corset with crinoline — displayed in a museum, stripped of its dress, exposed.
The corset: pink, stiffened with boning, with small bows on either side of the upper edge. Below it, the crinoline — a cage of rods and tapes, expanding dramatically to the sides. At the bottom of the corset, right at the junction with the crinoline — small pads with a floral pattern, attached on both sides.
In „The Genome Wardrobe” we’ve already undressed gowns and hairstyles. Time to undress them all the way.”
1. Corset and Crinoline
The corset with crinoline is a two-part construction — two separate layers of undergarments that together create the silhouette of an 18th-century woman.
[IMAGE: Tokyo, Japan – Circa 2015: Classic french corset at Madame Tussauds Museum in Odaiba. Samuel Ponce – Shutterstock]
The corset (corps à baleine) is a stiffened bodice worn directly against the body. Imagine a vest in which, instead of soft fabric, rigid rods are sewn in — boning — made of whalebone or reed. They prevent the corset from bending, holding the body in a stiff, cylindrical form narrowed at the waist. The front is laced — a cord passes through two rows of eyelets, pulling the front together. It works like a shoe lace: pull tight — the corset fits closer; loosen — it widens. On either side of the upper edge, two small bows are visible — tied, cinched.
The crinoline (panier) is a frame worn below the corset, under the skirt. Built from rods connected by tapes and covered with thin fabric in vertical stripes. The front of the crinoline is open — there is no fabric there. Instead, tapes emerge from beneath the panier’s fabric on one side, run across the open space, and tie with bows to tapes from the opposite side.
At the junction of corset and crinoline, a separate element is visible: small pads (buffantes) of floral-patterned fabric, attached to the corset on both sides, right at the boundary with the crinoline. These are not decoration — hip pads serve three specific functions: they add volume at the transition between the narrow corset and the wide crinoline, they smooth the silhouette — so the transition is not abrupt and harsh — and they support the weight of the dress worn over them.
Together they create a silhouette with two distinct zones: a narrow top (corset) and a wide bottom (crinoline). This proportion — a cinched waist transitioning into expansion — is the key to decoding.
The corset in the form of a boned bodice has existed since the 16th century — since the time Catherine de’ Medici introduced it to the French court. The panier appeared later — around 1709 in England and 1718–1719 in Paris. The peak of this combination was the 1740s–1750s, when panniers reached their largest dimensions.
2. The Protein — Potassium Channel Kir4.1 (PDB: 8I5M)
What is an ion channel?
Every cell in your body is surrounded by a membrane — a thin layer of fat that acts like the wall of a house: it separates the inside from the outside. But this wall is almost completely sealed — it doesn’t let through charged particles called ions (potassium, sodium, calcium ions). The problem is that the cell needs these ions to live — they generate electrical signals, maintain chemical balance, and drive life processes.
The solution? An ion channel — a protein embedded in the membrane that forms a tunnel. Like a door in a wall: it lets specific ions through while rejecting others.
What is Kir4.1?
[IMAGE: diagram — bottom: astrocyte (yellow) with neuron (blue) and capillary (pink); top: enlarged view of cell membrane with ion channel (purple) and K⁺ ions (white spheres) ART-ur – Shutterstock]
[Vector description:Astrocyte vector. Glial cells (neuroglia). Central nervous system. Dee-sign – Shutterstock]
The diagram shows two planes. At the bottom — an astrocyte: a yellow, star-shaped cell that wraps its arms around both a neuron (blue, on the left) and a blood vessel (pink, on the right). The astrocyte is a caretaker — it tends to the environment in which neurons work, like a gardener tending the soil around plants.
At the top — an illustrative diagram of an ion channel in a cell membrane. The blue spheres are fat molecules forming the membrane, the purple object embedded between them is the channel, and the white spheres on both sides are potassium ions (K⁺) flowing through the tunnel into the cell. The illustration shows the general principle of how a channel works — Kir4.1 operates in the same way in the astrocyte membrane.
Kir4.1 is an „inwardly rectifying” potassium channel — which simply means it lets potassium into the cell more easily than it lets it out. Like a door with a strong spring that opens more easily in one direction than the other. It belongs to the Kir channel family (from Inwardly Rectifying), and its gene is designated KCNJ10.
In the brain, Kir4.1 sits mainly on the processes of astrocytes — where they touch neurons and blood vessels. Astrocytes „clean up” excess potassium after neuronal activity — and Kir4.1 is the gate through which that potassium flows into the astrocyte.
But Kir4.1 has a darker side. Deep in the brain lies a small structure called the lateral habenula — a kind of disappointment center that activates when things don’t go our way. When Kir4.1 channels in the astrocytes of the habenula are too active — too open — they excessively buffer potassium around neurons, which indirectly silences those neurons beyond measure. The brain falls into a state of chronic „disappointment.” This is one of the mechanisms of depression.
How to fix it? Block the channel pore so that ions stop flowing. When the channel is closed, the habenula neurons regain normal activity. The 8I5M structure was solved precisely in this context: scientists were searching for a new class of antidepressants and needed to see the channel’s shape to design a molecule that would close its pore.
How is Kir4.1 built?
The 8I5M structure is Kir4.1 from rat, captured alongside a molecule called PIP2 — a lipid (fatty) cofactor without which the channel does not function. The structure was imaged using cryo-EM — a technique in which the protein is flash-frozen and photographed with an electron beam, yielding an image at 2.85 ångström resolution (less than one billionth of a meter — the scale of individual atoms).
The protein has a two-part architecture — as if it consisted of two floors:
Upper floor: TMD (transmembrane domain — the part sitting in the membrane). A narrow, rigid structure built from helices — spiral protein „rods.” Each of the channel’s four subunits contributes three such helices: TM1 (outer, touching the membrane lipids), TM2 (inner, lining the ion tunnel), and the slide helix (short, lying horizontally at the bottom, just above the waistline). The whole channel has twelve in total. Between TM1 and TM2 lies the selectivity filter — the narrowest point of the tunnel, which recognizes potassium ions by their size and lets only them through. It works like an airport gate that only lets passengers with the right ticket pass.
Waistline: PIP2. Between the upper and lower floors lies a transitional zone where PIP2 sits — a molecule that holds both floors together and enables the channel gate to open. Without PIP2, the channel does not function. How exactly this mechanism works — and what encodes it on the corset — you’ll see in section 4.
Lower floor: CTD (cytoplasmic domain — the part protruding into the cell interior). A wide, elaborate structure built mainly from beta sheets — flat, ribbon-like elements arranged side by side, like cards in a deck stood on edge. The CTD forms an additional tunnel — an extension of the ion channel — lined with charged amino acids responsible for the „rectifying” behavior of ion flow.
The Kir channel family comprises seven subfamilies (Kir1.x–Kir7.x). All share the same two-part architecture: narrow top, wide bottom — the same silhouette as a corset with crinoline.
3. Decoding — Level 1: Silhouette (cartoon)
[IMAGE: side-by-side — corset with crinoline vs 8I5M cartoon]
The „cartoon” view in the Mol* program displays the protein as colored spirals and ribbons — a simplified diagram that reveals the architecture. The silhouette of the Kir4.1 channel and the silhouette of the corset with crinoline are strikingly similar:
Undergarment element Protein element (8I5M) Corset — narrow, stiffened, cylindrical TMD — upper floor, narrow, embedded in the membrane Crinoline/panier — wide cage of rods and tapes CTD — lower floor, extensive network of beta sheets Boning — vertical, rigid rods maintaining shape Helices TM1, TM2, and slide helix — three „rods” per subunit, twelve in the channel Lacing — cords crossing regularly from top to bottom Alpha helices TM2 overlapping each other — forming the channel gate Bows — where the shoulder straps meet the corset body May encode loops connecting helices at the top of the channel Waistline — narrowing between corset and crinoline Slide helix zone — where PIP2 sits Floral-patterned pads PIP2 molecules Rods and tapes of the crinoline frame Beta sheets and loops of the lower floor
Boning = helices
The corset’s boning consists of rigid rods sewn into the fabric — they prevent the corset from collapsing. In the protein, helices serve the same role — spiral protein structures hard as springs. Without them the channel would collapse, just as a corset without boning would sag limply.
Kir channels have three helices per subunit — twelve in the entire channel. That’s the minimum in the world of ion channels. For comparison: voltage-gated channels (those that respond to electrical impulses) have six helices per subunit — the additional ones form a voltage sensor. Kir is a corset with the minimum number of bones — enough to maintain shape, but nothing superfluous. The lowest helix — the slide helix — sits right next to the pads (PIP2), at the waistline itself.
Bows — junction of shoulder straps and body
On either side of the corset’s upper edge, two bows are visible — attached precisely where the shoulder straps meet the front panel of the corset. This is not a random location — the bows sit at the point where two separate elements (the strap running from the back and the front panel) meet and must be permanently joined. In the protein, the tops of the transmembrane helices are connected by short extracellular loops — stretches of protein chain that link the end of one helix to the beginning of another. The bows may encode precisely these loops — bonds at the point where two separate structural elements meet at the top of the channel.
Lacing = alpha helices of the channel gate
Look at the corset’s lacing: the cords cross regularly, creating a repeating pattern of X after X after X from top to bottom. In the comparison image, in the upper floor of the protein, you see exactly the same motif: alpha helices TM2— spiral chains that overlap at regular intervals, crossing in the same pattern as the lacing cords.
The lacing encodes the TM2 helices on two levels simultaneously:
Appearance — the crossing pattern of the cords corresponds to the crossing alpha helices seen from the front. Regular X’s on the corset = regular helix crossings in the channel.
Function — tightening the lacing narrows the corset; loosening widens it. Similarly, the TM2 helices can move closer together — narrowing the tunnel and blocking ion flow — or move apart, widening it. Tightened lacing = closed gate. Loosened = open.
Crinoline = cytoplasmic domain (CTD)
The crinoline encodes the protein’s lower floor — the cytoplasmic domain — on three levels simultaneously:
Vertically striped fabric corresponds to beta sheets. Look at the comparison: on the panier’s fabric you see regular, vertical stripes running parallel from top to bottom. On the protein diagram (cartoon) in the lower part — the cytoplasmic domain — you see exactly the same motif: flat, wide ribbons arranged in parallel side by side, with arrows indicating the direction of the chain. These are beta sheets — one of the two basic building blocks of proteins (alongside the helix-spirals we saw in the upper part as boning). Helices are round and twisted like springs. Beta sheets from this perspective are flat and straight — like stripes on fabric. And that’s exactly how you see them in both images: flat, parallel, regular. But upon zooming in on beta sheets, you can see they’re not perfectly smooth — the protein chain runs in a zigzag up-down pattern, like an accordion. Flat from a distance, pleated up close — which is why scientists officially call them „pleated sheets.”
The open space at the front — where there is no fabric — is not emptiness. This is an intentional design: the opening reveals tapes connecting the two halves of the crinoline, running from one side to the other and tying with bows. In the comparison image, at the same location on the protein — in the lower, front part of the cytoplasmic domain — you see exactly the same motif: loops connecting adjacent beta strands — thin, like tiny wires — running from one ribbon to the next. These loops correspond to hydrogen bonds that hold parallel beta strands together in a stable structure. The open space at the front of the crinoline does not encode emptiness — it encodes exposed connections.
4. Decoding — Level 2: Close-up on the Waistline
[IMAGE: three panels — 1) surface TMD–CTD with PIP2 in orange, 2) corset close-up on waistline, 3) cartoon TMD–CTD with PIP2 in green ball-and-stick]
This is the most important close-up in this post. Three images — protein in surface fill, corset, protein in diagram — show the same location: the waistline.
In the top panel, the protein is displayed as a smooth solid (the so-called „surface” view — as if you covered the entire structure with a thin layer of plaster, hiding details but preserving the shape). At the transition line between the narrow top and wide bottom, orange protrusions are visible on both sides — PIP2 molecules. Rounded, puffy — like pads.
In the middle panel — the corset. At the bottom, on both sides, right at the boundary with the crinoline — pads of floral-patterned fabric.
In the bottom panel, the same protein, but in „cartoon” view — a diagram showing the internal architecture (spirals, loops, ribbons). PIP2 molecules are displayed as ball-and-stick models (green) — now their chemical structure is visible.
Pads = PIP2
The mapping works on two levels:
Shape of the pad = shape of the PIP2 molecule. The pad is rounded and convex — it protrudes from the corset like a small puff. The PIP2 molecule in the surface view (top panel) looks the same: a rounded protrusion sitting on the protein’s surface.
Floral pattern on the pad = chemical structure of PIP2. On the pad’s fabric, small flowers with petals are visible. In the ball-and-stick view (bottom panel), the PIP2 molecule reveals its internal architecture: the inositol ring — a six-membered sugar ring that looks like the central flower — with attached phosphate groups branching off to the sides like petals and stems. You can picture it as a daisy: the ring is the flower head, and the phosphate groups are the petals around it.
What does PIP2 do?
PIP2 (phosphatidylinositol 4,5-bisphosphate) is a fatty molecule with a sugar head that sits in the cell membrane. In the Kir4.1 channel, PIP2 holds the upper and lower floors together — and through this very act of holding, opens the channel gate. This is one mechanism, not two: by linking the domains in the right geometry, PIP2 pulls the TM2 helices into a position where the ion tunnel widens and ions can flow. Without PIP2, the domains disconnect, the gate closes — like a corset detached from its crinoline, unable to function properly.
The channel binds four PIP2 molecules — one per subunit. On the corset, we see two pads, but each is attached at two points. Total: two pads × two attachment points = four — exactly the number of PIP2 molecules in the channel.
5. Decoding — Level 3: Surface (molecular surface)
[IMAGE: 8I5M molecular surface, front view]
Switching from „cartoon” to „molecular surface” makes the spirals and ribbons disappear, replaced by a smooth solid — the protein’s true outline in space. It’s like the difference between an X-ray of a hand (you can see bones, joints, structure) and a photograph of that same hand from outside (you see only skin).
The silhouette is the same as in the diagram, but now the fill is visible: the narrow top (corset) passes through a distinct narrowing (waistline) into the wide bottom (crinoline). The proportions of the corset with crinoline are identical.
The protein looks the same from every side — front, side, back — because its symmetrical construction yields a nearly identical outline regardless of viewing angle. Just as a corset with crinoline encircles the body all the way around, the Kir4.1 channel surrounds the ion tunnel from all sides.
6. Conclusions — The Underwear of Depression
In „The Genome Wardrobe” series, every garment conceals a different protein. But this time it’s not a garment — it’s underwear. An element normally hidden beneath the dress, invisible to the world.
And this is the deepest metaphor of this post.
Kir4.1 is a protein whose dysfunction lies beneath the surface of depression — hidden, invisible, just as a corset is hidden beneath a gown. A patient with depression doesn’t know that in their lateral habenula, Kir4.1 channels are too active. The psychiatrist doesn’t see those channels — they see symptoms. Nobody looks at the underwear — everyone looks at the dress.
But it’s the underwear — the corset — that gives the silhouette its shape. It’s the corset that determines how the dress sits, how it looks, how a woman moves. It’s Kir4.1 that determines how astrocytes function, how habenula neurons process disappointment, whether a person copes with failure or falls into depression.
The 8I5M structure was solved in 2024 in the context of searching for new antidepressants — drugs that would close the channel gate, stopping the excessive flow of ions in the habenula.
The corset squeezes the body. An open Kir4.1 silences neurons — it hyperpolarizes them, lowering their electrical potential so far that they cannot send a signal. Like turning a radio down to zero — the equipment works, but nothing can be heard. An antidepressant tightens the corset’s lacing — it closes the channel gate (TM2 helices), blocking ion flow. Paradoxically, it is precisely this closure of flow that restores normal neuronal activity — when excess potassium stops flowing into the cell, the neuron returns to its proper potential and can send signals again.
But there is something even deeper here. Someone in the 18th century — a seamstress, a craftsman, a designer — created a construction that mirrors a protein not solved until 2024. Boning arranged like transmembrane helices. Lacing functioning like an ion channel gate. Floral-patterned pads sitting in exactly the place where PIP2 holds two domains together. Every element in its place, in the correct proportion, with the proper function.
Science needed a cryogenic electron microscope, supercomputers, and decades of research to see what 18th-century underwear showed with the naked eye. The structure was here from the beginning — hidden beneath the dress, waiting for someone to remove the outer layer and look at what was underneath.
18th-century underwear waited over two centuries for its diagnosis. And the protein — this molecular corset — is only now beginning to receive one.
Image search and matching, analysis and elaboration: Tomasz Mikulski – Cell God: 08/2026
BIBLIOGRAPHY
Molecular structures and biology
Berman, H. M., Westbrook, J., Feng, Z., et al. (2000). „The Protein Data Bank.” Nucleic Acids Research, 28(1), 235–242. https://www.rcsb.org/
Protein Data Bank. (2024). „8I5M: Rat Kir4.1 in complex with PIP2.” https://www.rcsb.org/structure/8I5M
Zhou, X., Zhao, C., Xu, H., et al. (2024). „Pharmacological inhibition of Kir4.1 evokes rapid-onset antidepressant responses.” Nature Chemical Biology, 20, 857–866. https://doi.org/10.1038/s41589-024-01555-y
Hibino, H., Inanobe, A., Furutani, K., Murakami, S., Findlay, I., & Kurachi, Y. (2010). „Inwardly rectifying potassium channels: their structure, function, and physiological roles.” Physiological Reviews, 90(1), 291–366. https://doi.org/10.1152/physrev.00021.2009
Tao, X., Avalos, J. L., Chen, J., & MacKinnon, R. (2009). „Crystal structure of the eukaryotic strong inward-rectifier K+ channel Kir2.2 at 3.1 Å resolution.” Science, 326, 1668–1674. https://doi.org/10.1126/science.1180310
Fashion history
Sew Honest https://www.sewhonest.co.uk/2015/02/history-sunday-brief-history-of-corsets.html<