Molecular cloning of proteoglycan core proteins

Recombinant DNA methods have been used to analyse core proteins of two different proteoglycans, one from a rat yolk sac tumour and the other from human fibroblasts and fetal membrane tissue. The processed core protein of the yolk sac tumour proteoglycan is a 104-amino acid polypeptide. This polypeptide contains a 49-amino acid serine-glycine repeat which clearly serves as the chondroitin sulphate attachment region. Genomic and mRNA blots suggest that this core protein is a member of a multigene family the members of which share the Ser-Gly repeat. The fibroblast/fetal membrane proteoglycan has a 329-amino acid core protein which is also processed from a larger precursor. This core protein contains three individual Ser-Gly dipeptides, one of which is known to be substituted with a chondroitin/dermatan sulphate side-chain. The availability of proteoglycan cDNA clones will facilitate gene transfer studies aimed at identifying the recognition sequences for the addition of the glycosaminoglycan. Gene transfer should also allow studies on the effects of proteoglycan expression on cellular properties such as adhesion and tumorigenicity.