title: Alternative splicing model for the synthesis and secretion of the 20 kilodalton form of rat growth hormone.
abstract: The characterization of a 20 kilodalton (20 kD) variant of rat growth hormone is reported. The 20 kD variant from rat pituitary gland extracts was identified on Western immunoblots of polyacrylamide gels. It was also shown that pituitary tissue maintained in culture secretes the 20 kD form. A rat growth hormone cDNA fragment was used as a probe in S1 nuclease mapping experiments of rat pituitary poly (A) mRNA to detect the presence of two growth hormone mRNAs in the rat pituitary gland. The protected mRNAs correspond to the predicted sizes that would encode the 22 kD and 20 kD forms of growth hormone. The site of variation between the mRNAs maps to a potential alternative 3' splice site in the 5' end of exon 3 of the coding sequence. The results support the hypothesis that the 20 kD variant in rat is the product of an mRNA alternatively spliced in exon 3, as is the case for the human growth hormone.
mesh_terms: D000818:Animals; D001483:Base Sequence; D046508:Culture Techniques; D004247:DNA / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D013006:Growth Hormone / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D007118:Immunoassay; D008297:Male; D009693:Nucleic Acid Hybridization; D010903:Pituitary Gland, Anterior / Q000378:metabolism*; D012326:RNA Splicing; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D012333:RNA, Messenger; D013006:Growth Hormone; D004247:DNA