This short domain is a coiled coil structure and has a single cysteine residue at the start which is likely to form a di-sulfide bridge with a corresponding cysteine in an upstream EGF (Pfam:PF00008) domain thereby spanning a VWA (Pfam:PF00092) domain. All three domains can be associated together as in the cartilage matrix protein matrilin, where this domain is likely to be responsible for oligomerisation [2].

1: Heteronuclear NMR assignments and secondary structure of the coiled coil trimerization domain from cartilage matrix protein in oxidized and reduced forms. Wiltscheck R, Kammerer RA, Dames SA, Schulthess T, Blommers MJ, Engel J, Alexandrescu AT; Protein Sci. 1997;6:1734-1745. PMID:9260286

2: Primary structure of matrilin-3, a new member of a family of extracellular matrix proteins related to cartilage matrix protein (matrilin-1) and von Willebrand factor. Wagener R, Kobbe B, Paulsson M; FEBS Lett. 1997;413:129-134. PMID:9287130