collagen 4 alpha-6 (COL4A6)

Function

• type 4 collagen is the major structural component of glomerular basement membranes (GBM), forming a 'chicken-wire' meshwork together with laminins, proteoglycans & entactin/nidogen
• Pro at the third position of the tripeptide repeating unit (G-X-Y) are hydroxylated in some or all of the chains
• type 4 collagen contains numerous Cys which are involved in intermolecular & intramolecular disulfide bonding
  • 12 of these, located in the NC1 domain, are conserved in all known type 4 collagen
• the trimeric structure of the NC1 domains is stabilized by covalent bonds between Lys & Met residues (putative)
• there are six type 4 collagen isoforms, each of which can form a triple helix structure with 2 other chains to generate type 4 collagen network

Structure

• alpha chains of type 4 collagen have
  • a non-collagenous domain (NC1) at their C-terminus
  • frequent interruptions of the G-X-Y repeats in the long central triple-helical domain (which may cause flexibility in the triple helix)
  • a short N-terminal triple-helical 7S domain
• belongs to the type 4 collagen family
• contains 1 collagen 4 NC1 (C-terminal non-collagenous) domain

Compartment

• secreted, extracellular space
• extracellular matrix, basement membrane

Alternative splicing

named isoforms=2; A, B

Pathology

• deletions covering the N-terminal regions of COL4A5 & COL4A6, which are localized in a head-to-head manner, are found in the chromosome Xq22.3 centromeric deletion syndrome

More general terms

• collagen subunit

Component of

• collagen type-4

Database

• Entrez gene: http://www.ncbi.nlm.nih.gov/sites/entrez?db=gene&cmd=Retrieve&dopt=Graphics&list_uids=1288
• Kegg: http://www.genome.jp/dbget-bin/www_bget?hsa:1288
• OMIM: https://mirror.omim.org/entry/303631
• UniProt: http://www.uniprot.org/uniprot/Q14031.html