= Collagen IV protomer
{c}
A <Collagen IV protomer> is a three-chain molecular unit of <Collagen IV> that assembles with other units to form a <basement membrane> network. Much of its length has a <collagen triple helix>, while its <C-terminus> presents three <Collagen IV NC1 domains>. Association of two such ends forms a <Collagen IV NC1 hexamer>.<A Sulfilimine Bond Identified in Collagen IV by Roberto Vanacore and others>[Introduction and Figure 3; triple-helical protomers and end-to-end network assembly]{ref}
The organizational levels can be counted separately. Ten intact three-chain <Collagen IV protomers> contain thirty <polypeptide> chains, but this count does not describe how the ten units are connected. A six-subunit NC1 junction joins two protomers at one end; it does not convert either protomer into a six-chain molecule.
The term is therefore useful when moving between a <protein>'s molecular composition and the architecture of the scaffold it builds. Identifying a three-chain unit answers a different question from identifying the contacts and <covalent bonds> between neighbouring units.
Back to article page
