TY - JOUR
T1 - Lack of phosphorylation of lipocortin I in A431 epidermoid carcinoma cells treated with phorbol esters
AU - William, Felicia
AU - Haigler, Harry T.
AU - Kraft, Andrew S.
N1 - Funding Information:
Acknowledements: This work was supportedb y Amercan Cancer Society grant BC 522 and grant CA42533 from the National Institutes of Health to ASK. and grant HD-00700 to H.H. To wish to thank Dr. S. Cohen for the gift of anti-lipocortin I antibody, Drs. C. Creutz for chromobindins, V.L. Smith for calcemidins,T .C. Sudhof for calectrins, and B. Pepinsky for lipocortin II.
PY - 1989/4/28
Y1 - 1989/4/28
N2 - To examine in vivo phosphorylation of lipocortin I we made use of a polyclonal antibody to an amino terminal peptide of lipocortin I. This antibody does not recognize any other member of the annexin protein family, and can both immunoprecipitate lipocortin I and recognize this protein on western blots. Using cleaved forms of lipocortin I, we have been able to demonstrate that protein kinase C phosphorylates this protein in vitro within the first 29 amino terminal amino acids. However, the addition of phorbol esters to A431 cells over a wide range of concentrations and for varying periods of time did not stimulate the phosphorylation of this protein. Since in vitro lipocortin I is an excellent substrate for all three isoforms, alpha, beta, gamma, of protein kinase C, the discrepancy in these finding is not secondary to the presence of varying forms of this protein kinase within different cell types.
AB - To examine in vivo phosphorylation of lipocortin I we made use of a polyclonal antibody to an amino terminal peptide of lipocortin I. This antibody does not recognize any other member of the annexin protein family, and can both immunoprecipitate lipocortin I and recognize this protein on western blots. Using cleaved forms of lipocortin I, we have been able to demonstrate that protein kinase C phosphorylates this protein in vitro within the first 29 amino terminal amino acids. However, the addition of phorbol esters to A431 cells over a wide range of concentrations and for varying periods of time did not stimulate the phosphorylation of this protein. Since in vitro lipocortin I is an excellent substrate for all three isoforms, alpha, beta, gamma, of protein kinase C, the discrepancy in these finding is not secondary to the presence of varying forms of this protein kinase within different cell types.
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U2 - 10.1016/0006-291X(89)92457-1
DO - 10.1016/0006-291X(89)92457-1
M3 - Article
C2 - 2524194
AN - SCOPUS:0024980016
SN - 0006-291X
VL - 160
SP - 474
EP - 479
JO - Biochemical and Biophysical Research Communications
JF - Biochemical and Biophysical Research Communications
IS - 2
ER -