Identification of four lipocortin proteins and phosphorylation of lipocortin I by protein kinase C in cytosols of porcine thyroid cell cultures.
Four proteins of the lipocortin family, lipocortin I (35 kDa), lipocortin II (36 kDa), lipocortin V (32 kDa) and lipocortin VI (67-70 kDa), were identified in the cytosols of 2-day-old cultures of thyroid cells. Only lipocortin I was phosphorylated in vitro in fully differentiated, thyroid stimulating hormone-treated cells (0.1 mU/ml). Protein kinase C was the only kinase activity which phosphorylated lipocortin I. Phosphorylation shifted its pI from 6.9 to 6.6. The in vitro phosphorylation of lipocortin I was impaired in cultures exposed for 2 days to phorbol ester (10(-7) M), although it was present in both the cytosol and the particulate fraction of these cells.
Antonicelli
F
F
Laboratoire de Biochimie, UFR Sciences, Reims, France.
Omri
B
B
Breton
M F
MF
Rothhut
B
B
Russo-Marie
F
F
Pavlovic-Hournac
M
M
Haye
B
B
D000818:Animals; D017302:Annexins; D015153:Blotting, Western; D002135:Calcium-Binding Proteins / Q000302:isolation & purification / Q000378:metabolism*; D002478:Cells, Cultured; D003600:Cytosol / Q000378:metabolism; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D006023:Glycoproteins / Q000378:metabolism*; D008970:Molecular Weight; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D013552:Swine; D013961:Thyroid Gland / Q000187:drug effects / Q000378:metabolism*; D013972:Thyrotropin / Q000494:pharmacology
D017302:Annexins; D002135:Calcium-Binding Proteins; D006023:Glycoproteins; D013972:Thyrotropin; D011493:Protein Kinase C