The Role of Hydroxylation of Proline in the Antigenicity of Basement Membrane Collagen¹

Rabbit antibodies to bovine basement membrane collagen were used to compare the antigenic determinants of rat parietal yolk sac basement membrane [¹⁴C]procollagen with [¹⁴C]protocollagen. Basement membrane [¹⁴C]protocollagen was found to be less antigenic than basement membrane [¹⁴C]procollagen. Hydroxylation of basement membrane [¹⁴C]protocollagen, either intracellularly or in vitro with protocollagen prolyl hydroxylase, resulted in restoration of antigenicity. The difference in antigenicity observed between basement membrane [¹⁴C]procollagen and basement membrane [¹⁴C]protocollagen appeared to depend primarily upon the presence of hydroxyproline in the collagen molecule. Glucosylgalactosylhydroxylysine was found to be unimportant for antigenicity.