Molecular cloning and sequence analysis of a chondroitin sulfate proteoglycan cDNA.

Abstract

The identification and DNA sequence of a chondroitin sulfate proteoglycan core protein c[complementary]DNA is reported. A cDNA clone, pPG1, was selected from a rat yolk sac tumor poly(A)+ RNA-derived cDNA library by using synthetic oligonucleotides predicted from the NH2-terminal peptide sequence of the mature chondroitin sulfate proteoglycan. The resulting sequence analysis demonstrated that the 874-base-pair pPG1 clone contained the complete coding region of the mature proteoglycan core protein as well as 5'' and 3'' flanking sequences. The 104 amino acid proteoglycan core protein sequence reveals that the core protein is composed of 3 regions, the most striking of which is the central 49 amino acid region composed of alternating Se ane Glc residues. This region clearly functions as the acceptor site for the attachment of chondroitin sulfate side chains. The SE-Gly repeat region is flanked by a 14 amino acid NH2-terminal region identical to the NH2-terminal sequence of the proteoglycan obtained by amino acid sequencing and a 41 amino acid COOH-terminal region. NA transfer blot hybridizations of poly(A)+ mRNA from rat yolk sac tumor cells with nick-translated pPG1 reveal a single mRNA of .simeq. 1300 nucleotides. The possibility of detecting mRNA and genomic sequences for other proteoglycans with a Ser-Gly repeat by using this cDNA clone is discussed.