期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：1983
卷号：80
期号：3
页码：878-881
DOI：10.1073/pnas.80.3.878
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：The phosphorylation of proteins released into the medium of bovine parathyroid gland slices or isolated cells incubated with 32Pi has been investigated. The primary protein phosphorylated had a Mr of 68,000 and coeluted with newly synthesized parathyroid secretory protein (PSP) on Bio-Gel chromatography and on polyacrylamide gel electrophoresis. Isoelectric focusing of double-labeled samples ([35S]methionine and 32Pi) revealed comigration of the two radioactive markers at a pH of 4.6, which was similar to that of purified PSP. Phosphorylation of the Mr 68,000 protein was also demonstrated in cell homogenates incubated with [gamma-32P]ATP; the Mr 68,000 protein was the predominant labeled protein. Increasing quantities of calcium, with and without added EGTA, caused a progressive decrease in phosphorylation of the protein. These studies demonstrate that PSP is readily phosphorylated in parathyroid cells, that the degree of phosphorylation is inversely proportional to calcium concentration, and that PSP is the major phosphorylated protein released from the gland. The relationship of phosphorylation to the potential physiologic importance of PSP remains to be determined.
