Abstract
Podocytes are crucial cells of the glomerular filtration unit and playing a vital role at the interface of the blood-urine barrier. Podocyte slit-diaphragm is a modified tight junction that facilitates size and shape-dependent permselectivity. Several proteins including podocin, nephrin, CD2AP, and TRPC6 form a macromolecular assembly and constitute the slit-diaphragm. Podocin is an integral membrane protein attached to the inner membrane of the podocyte via a short transmembrane region (101-125). The cytosolic N- and C-terminus help podocin to attain a hook-like structure. Podocin shares 44% homology with stomatin family proteins and similar to the stomatin proteins, podocin was shown to associate into higher-order oligomers at the site of slit-diaphragm. However, the stoichiometry of the homo-oligomers and how it partakes in the macromolecular assemblies with other slit-diaphragm proteins remains elusive. Here we investigated the oligomeric propensity of a truncated podocin construct (residues:126-350). We show that the podocin domain majorly homo-oligomerize into a 16mer. Circular dichroism and fluorescence spectroscopy suggest that the 16mer oligomer has considerable secondary structure and moderate tertiary packing.
Competing Interest Statement
The authors have declared no competing interest.
Abbreviations
- SD
- slit-diaphragm
- GFB
- Glomerular filtration barrier
- CD2AP
- CD-2 associated protein
- TRPC6
- Transient receptor potential cation channel subfamily C member 6
- ZO-1
- Zonula occludens-1
- NEPH
- Nephrin-like protein
- NS
- Nephrotic syndrome
- SRNS
- steroid-resistant NS
- NPHS1 & 2
- Nephrotic syndrome-type I and type II
- IDRs
- Intrinsically disordered regions
- SEC
- Size-exclusion chromatography
- MALS
- multi-angle light scattering
- CD
- Circular dichroism