Phorbol ester induces phosphorylation of the 80 kilodalton murine interleukin 1 receptor at a single threonine residue.
The cytoplasmic domains of some cell surface receptors become phosphorylated in cells treated with phorbol esters. The present study was undertaken in order to determine whether this is also true of the 80 kDa interleukin 1 receptor (IL1R). Recombinant murine IL1R, transfected into chinese hamster ovary (CHO) cells or murine fibroblasts, was immunoprecipitated from [32P]orthophosphate-labelled cells. IL1R phosphorylation was only detected in cells pretreated with phorbol 12-myristate 13-acetate (PMA) and occurred solely on phosphothreonine. In contrast to a previous report, little or no IL1R phosphorylation occurred in response to IL1. By using a truncated receptor and receptors in which threonine residues were changed to alanines, we established that Thr537, near the carboxy-terminus, is the major site of PMA-induced phosphorylation. The human IL1R has a different sequence at this locus, and is apparently not phosphorylated. Binding studies showed that PMA-induced phosphorylation had no discernible effect on ligand binding or internalization.
Bird
T A
TA
Department of Biochemistry, Immunex Corporation, Seattle, Washington 98101.
Woodward
A
A
Jackson
J L
JL
Dower
S K
SK
Sims
J E
JE
D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D006801:Humans; D007375:Interleukin-1 / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D010710:Phosphates / Q000378:metabolism*; D010766:Phosphorylation; D010769:Phosphothreonine / Q000032:analysis; D011971:Receptors, Immunologic / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins / Q000378:metabolism; D013601:T-Lymphocytes / Q000276:immunology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D013912:Threonine; D014162:Transfection
D007375:Interleukin-1; D010710:Phosphates; D011971:Receptors, Immunologic; D017472:Receptors, Interleukin-1; D011994:Recombinant Proteins; D010769:Phosphothreonine; D013912:Threonine; D013755:Tetradecanoylphorbol Acetate