Protein phosphorylation in intact lymphocytes stimulated by Concanavalin A

Tingchung Wang, John E. Foker, Alvin M. Malkinson

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18 Scopus citations

Abstract

The phosphorylation of proteins in intact mouse spleen lymphocytes was monitored following mitogenic activation. Little change in the autoradiographic patterns of phosphorylated protein fractionated by polyacrylamide gel electrophoresis occurred during the first 8 h after Concanavalin A (conA) treatment. The intensity of 32P incorporation into two proteins of 135 000 and 150 000 mol. wt began to increase, relative to control cells, 10 h after conA treatment and was maximal at 50 h. This increased phosphorylation followed the rise in RNA synthesis but preceded the onset of DNA synthesis. In addition to this temporal link between enhanced phosphorylation of these proteins and the initiation of DNA synthesis, various agents which inhibited the onset of S phase also blocked the phosphorylation of both proteins. Such treatments included the displacement of conA from its surface receptors by α-methyl-mannoside (αMM), the omission of serum from the culture medium, and the presence of indomethacin. The similar time courses of phosphorylation and responses to various proliferation inhibitors supports the idea that the 135 000 and 150 000 mol. wt proteins have a common physiological function. These proteins may be involved in the progression of stimulated lymphocytes toward S phase, and their phosphorylation may be an important regulatory event in this sequence.

Original languageEnglish (US)
Pages (from-to)409-415
Number of pages7
JournalExperimental Cell Research
Volume134
Issue number2
DOIs
StatePublished - Aug 1981

Bibliographical note

Funding Information:
We thank Heman Rengifo and Cathy Marquardt for their excellent technical assistance, and Drs Alan Hoouer and Donald Ross for their hetnful comments on the manuscript. This work was supported by a grant from Medical Education and Research Founda-son MERF 8236 (J. E. F.); NIH Grant GM 22492 (A. M. M.); and a Basil O’Connor Starter Grant from the National Foundation( A. M. M.).

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