Studies on the Gene Expression and Physiological Significance of novel Prolactin-Like Proteins in Bovine Placenta

点击翻译按钮获取中文摘要

Four novel prolactin-like hormone cDNA clones have been isolated from a bovine term placenta cDNA library. We designated these clones as bovine prolactin-like protein (bPLP)-I, II. III and IV. bPLP-I, II, III, IV showed 50, 48, 43 and 48% homology of amino acid sequence with that of bovine prolactin, respectively. With bovine growth hormone, however, they showed only 23, 23, 22 and 22% homology, respectively. bPLP-I, on the other hand, was identical except for the N-terminal amino acid residue with bovine placental lactogen. bPLP-I has Val as N-terminal. when bovine placental lactogen has Ala for that position. Predicted mature forms of bPLP-I, II, III and IV are composed of 201, 202, 203 and 201 amino acid residues, respectively. Gene expressions of these four novel prolactin-like hormones the in bovine placenta have been analyzed by Northern blot hybridization and turned out to be stage-specific being maximal in the full-term-placenta. Thus, four novel bovine placental hormones bPLP-I, II, III and IV, resembled prolactin more closely than a growth hormone, and were distinct from placental lactogen. And these new hormones were considered to play important roles in metabolism and growth of the bovine fetus.