Translation and characterization of messenger RNAs in differentiating chicken cartilage.

Abstract

Total RNA, prepared from chicken limb bud cultures undergoing differentiation to cartilage, was translated in a wheat germ cell-free protein-synthesizing system. Antibodies against chondroitin sulfate proteoglycan core protein immunoprecipitate a single component which migrates as a protein of 340,000 daltons in sodium dodecyl sulfate-polyacrylamide gels. The mRNA for this protein sediments at approximately 27 S in 70% formamide or aqueous sucrose gradients. The 340,000 dalton protein is present in cell-free translation products directed by RNA prepared from limb bud cultures and sternae and is absent in cell-free translation directed by RNA prepared from embryonic calvaria or liver. The level of synthesis of this protein is greatly reduced when RNA prepared from limb bud cultures inhibited from differentiation by BrdUrd [bromodeoxyuridine] is used. (Pre)pro.alpha.1(I), -.alpha.2(I) and -.alpha.1(II) collagen bands were identified on gels by electrophoresis of collagenase-digested or immunoprecipitated cell-free translation products directed by RNA from differentiating limb bud cultures, embryonic sternae and embryonic calvaria.