Proteomics analysis of growth hormone isoforms in the human pituitary.
In order to elucidate the roles of human growth hormone (hGH) in the normal (control) pituitary and in adenomas, the hGH isoforms in the human pituitary were analyzed with two-dimensional gel electrophoresis, immobilized metal affinity column (Ga(+3)) chromatography, mass spectrometry (MS), and bioinformatics. Twenty-four hGH-containing proteins, with significantly different expression proportions of their isoforms were found. The proportions of isoforms were as follows: isoform 1 (87.5%) > isoform 2 (8.1%) > isoform 3 (3.3%) > isoform 4 (1.1%). Deamidation of asparagine to aspartate was identified with matrix-assisted laser desorption/ionization-time of flight MS. Tandem mass spectrometry data demonstrated that hGH is a phosphoprotein (spot 6); phosphorylation was found at Ser-77 in the tryptic peptide (68)YSFLQNPQTSLCFSESIPTPSNR(90), at Ser-176 in the tryptic peptide (172)FDTNSHNDDALLK(184), and at Ser-132 in the peptide (126)SLVYGASDSNVYDLLK(141). The phosphorylation sites at Ser-77 and Ser-176 were consistent with computer-program predictions (NetPhos). These results provide novel clues for further studies of the functions, and mechanisms of action, of hGH in the human pituitary and in growth hormone-related diseases.
Zhan
Xianquan
X
Charles B. Stout Neuroscience Mass Spectrometry Laboratory, University of Tennessee Health Science Center, Memphis, TN 38163, USA.
Giorgianni
Francesco
F
Desiderio
Dominic M
DM
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D019295:Computational Biology; D019382:Human Growth Hormone / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D010902:Pituitary Gland / Q000737:chemistry*; D020033:Protein Isoforms / Q000032:analysis* / Q000235:genetics / Q000378:metabolism; D011499:Protein Processing, Post-Translational; D020543:Proteome / Q000032:analysis*; D040901:Proteomics; D020539:Sequence Analysis, Protein
D020033:Protein Isoforms; D020543:Proteome; D019382:Human Growth Hormone