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Proteomics analysis of growth hormone isoforms in the human pituitary
Author(s) -
Zhan Xianquan,
Giorgianni Francesco,
Desiderio Dominic M.
Publication year - 2005
Publication title -
proteomics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.26
H-Index - 167
eISSN - 1615-9861
pISSN - 1615-9853
DOI - 10.1002/pmic.200400987
Subject(s) - deamidation , gene isoform , proteomics , phosphoprotein , chemistry , peptide , asparagine , biochemistry , mass spectrometry , tandem mass spectrometry , phosphorylation , microbiology and biotechnology , biology , chromatography , amino acid , enzyme , gene
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.