THE 1.6 ANGSTROMS STRUCTURE OF THE KUNITZ-TYPE DOMAIN FROM THE ALPHA3 CHAIN OF THE HUMAN TYPE VI COLLAGEN
[CO6A3_HUMAN] Defects in COL6A3 are a cause of Bethlem myopathy (BM) [MIM:158810]. BM is a rare autosomal dominant proximal myopathy characterized by early childhood onset (complete penetrance by the age of 5) and joint contractures most frequently affecting the elbows and ankles.     Defects in COL6A3 are a cause of Ullrich congenital muscular dystrophy (UCMD) [MIM:254090]; also known as Ullrich scleroatonic muscular dystrophy. UCMD is an autosomal recessive congenital myopathy characterized by muscle weakness and multiple joint contractures, generally noted at birth or early infancy. The clinical course is more severe than in Bethlem myopathy. 
[CO6A3_HUMAN] Collagen VI acts as a cell-binding protein.
Publication Abstract from PubMed
The C-terminal Kunitz-type domain from the alpha 3 chain of human type VI collagen (C5), a single 58 amino acid residue chain with three disulfide bridges, was cloned, expressed and crystallized in a monoclonic form, space group P2(1), with a = 25.7 A, b = 38.2 A, c = 28.8 A and beta = 109 degrees. The structure was resolved by molecular replacement, using Alzheimer's protein precursor inhibitor and bovine pancreatic trypsin inhibitor three-dimensional structures as search models. The molecule with one sulfate ion and 43 associated water molecules was refined by XPLOR to an R-factor of 18.9% at 1.6 A. The molecule was not degraded by trypsin and did not inhibit trypsin or tested serine proteases. As opposed to the other Kunitz family members, C5 demonstrates left-handed chirality of the Cys14-Cys38 disulfide bond. Inversion of the Thr13 carbonyl and bulky side-chains at the interface with trypsin in a model of the C5-trypsin complex may explain the lack of inhibition of trypsin.
The 1.6 A structure of Kunitz-type domain from the alpha 3 chain of human type VI collagen.,Arnoux B, Merigeau K, Saludjian P, Norris F, Norris K, Bjorn S, Olsen O, Petersen L, Ducruix A J Mol Biol. 1995 Mar 10;246(5):609-17. PMID:7533217
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.