[Construction of cDNA clones encoding for cartilage proteoglycan core protein]

In order to investigate cartilage proteoglycan mRNAs and genes, a cDNA expression library was constructed from chick embryonic sternal mRNAs, and cDNA clones encoding for chondroitin sulfate proteoglycan core protein were screened from the library. Total RNA extracted from chick embryonic sterna was translated in a cell-free system using rabbit reticulocyte lysate. Immunoprecipitation of products of cell-free translation using antiserum against cartilage proteoglycan yielded a component of about 340 kd polypeptide. This polypeptide is most likely the translational product of proteoglycan core protein mRNA. A chicken embryo sternal cartilage cDNA library, created in the plasmid expression vector pUC 9, was screened for sequences coding for immunologically detectable core protein, and two cDNA clones were isolated. Northern blot hybridization of sternal cartilage RNA revealed a single mRNA of about 8.1 kb for proteoglycan core protein.