TY - JOUR
T1 - Phosphorylation of prolactin
AU - Oetting, W. S.
AU - Tuazon, P. T.
AU - Traugh, J. A.
AU - Walker, A. M.
N1 - Copyright:
Copyright 2004 Elsevier B.V., All rights reserved.
PY - 1986
Y1 - 1986
N2 - Rat prolactin exhibits microheterogeneity when examined in electrophoretic systems, running as three isoforms having the same molecular weight but different net charges (prolactins 1, 2, and 3 with isoform 3 being the most acidic). As there is precedent for the phorphorylation of a pituitary hormone and phosphorylation is a common cause of microheterogeneity, we examined the possibility that rat prolactin existed in differentially phosphorylated forms. The investigation included examinations of rat prolactin phosphorylation both in vitro and in vivo. For the in vitro studies, purified rat prolactin was incubated with [γ-32P]ATP and low levels of each of five purified protein kinases. Phosphorylated rat prolactin was identified by autoradiography of silver-stained one- and two-dimensional gels. For the in vivo studies, rat anterior pituitary cells in primary culture were incubated in the presence of H3 32PO4 for 2 or 12 h, after which time the proteins were extracted from the cells, cold acetone-precipitated, or immunoprecipitated and run on two-dimensional gels. We report (a) the in vitro phosphorylation of rat prolactin by cAMP-dependent protein kinase, casein kinase I, protease-activated kinase I, and the calcium/phospholipid-dependent kinase, (b) that phosphorylation with these kinases results in phosphate incorporation only into isoforms 2 and 3, and (c) the phosphorylation of prolactin in rat pituitary cells in primary culture.
AB - Rat prolactin exhibits microheterogeneity when examined in electrophoretic systems, running as three isoforms having the same molecular weight but different net charges (prolactins 1, 2, and 3 with isoform 3 being the most acidic). As there is precedent for the phorphorylation of a pituitary hormone and phosphorylation is a common cause of microheterogeneity, we examined the possibility that rat prolactin existed in differentially phosphorylated forms. The investigation included examinations of rat prolactin phosphorylation both in vitro and in vivo. For the in vitro studies, purified rat prolactin was incubated with [γ-32P]ATP and low levels of each of five purified protein kinases. Phosphorylated rat prolactin was identified by autoradiography of silver-stained one- and two-dimensional gels. For the in vivo studies, rat anterior pituitary cells in primary culture were incubated in the presence of H3 32PO4 for 2 or 12 h, after which time the proteins were extracted from the cells, cold acetone-precipitated, or immunoprecipitated and run on two-dimensional gels. We report (a) the in vitro phosphorylation of rat prolactin by cAMP-dependent protein kinase, casein kinase I, protease-activated kinase I, and the calcium/phospholipid-dependent kinase, (b) that phosphorylation with these kinases results in phosphate incorporation only into isoforms 2 and 3, and (c) the phosphorylation of prolactin in rat pituitary cells in primary culture.
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M3 - Article
C2 - 3003080
AN - SCOPUS:0022998807
SN - 0021-9258
VL - 261
SP - 1649
EP - 1652
JO - Journal of Biological Chemistry
JF - Journal of Biological Chemistry
IS - 4
ER -