Abstract
Calcium-dependent protein phosphorylation may be a critical step in the stimulated secretion of anterior pituitary hormones. We have noted the existence of a number of calcium-calcium/calmodulin-, and calcium/phospholipid-dependent phosphoproteins in the normal rat anterior pituitary. Cell extracts were prepared from anterior pituitary glands of male rats and phosphorylated with [gamma 32P]ATP in the presence or absence of calcium, calmodulin, and phosphatidylserine. The samples were electrophoresed on SDS-PAGE gels, autoradiographs prepared, and phosphate incorporation into specific proteins quantitated with microdensitometry. Calcium alone significantly stimulated the phosphorylation of proteins with molecular weights of 80.0-, 62.0-, 51.0-, 30.5-, and 25.0-kDa. The phosphorylation of 21.5-, 51.0-, and 80.0-kDa MW phosphoproteins was found to be phospholipid dependent. The phosphorylation of 62.0-, 51.0-, 33.0-, 30.5-, and 25.0-kDa MW phosphoproteins was found to be calcium/calmodulin kinase dependent. Calcium/calmodulin also inhibited phosphorylation of the 80.0-kDa phosphoprotein.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
