The significance of Ser1029 of the heat‐stable enterotoxin receptor (STaR): Relation of STa‐mediated guanylyl cyclase activation and signaling by phorbol myristate acetate

FEBS Letters

Ian Padilla, Philip¹ 

[1] Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852, Japan

关键词: Heat-stable enterotoxin receptor;    Guanylyl cyclase;    Phorbol myristate acetate;    STa;    heat-stable enterotoxin;    STh;    heat-stable enterotoxin produced by a human strain of Escherichia coli;    STaR;    heatstable enterotoxin receptor;    GC;    guanylyl cyclase;    PMA;    phorbol 12-myristate 13-acetate;    PKC;    protein kinase C;    SDS;    sodium dodecyl sulfate;    PAGE;    polyacrylamide gel electrophoresis;    DMEM;    Dulbecco's modified Eagle's medium;   

DOI  :  10.1016/0014-5793(96)00284-0

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

To characterize Ser¹⁰²⁹ in STaR at a consensus sequence of phosphorylation site by PKC, two mutants of mS1029A with replacement of Ser¹⁰²⁹ to Ala¹⁰²⁹ and CΔ1029 lacking 22 amino acids including Ser¹⁰²⁹ were prepared. Preincubation of the wild type-STaR (wt-STaR) transfectant with 1 μM PMA caused additional STa-mediated guanylyl cyclase (GC) activation compared to control, whereas the mS1029A- and CΔ1029-transfected cells did not show a similar enhanced GC activation by PMA. After metabolic labeling with [³²P]phosphate, transfected cells with wt-STaR and mutants were incubated with 1 μM PMA. Subsequent ³²P-radiolabeled proteins were immunoprecipitated using anti-STaR antibody, and analyzed by autoradiography after separation on SDS-PAGE. The immunoprecipitated wt-STaR but not mS1029A and CΔ1029 had a significant radioactivity. These results suggest that the effect of PMA on wt-STaR transfectants may be caused by phosphorylation of Ser¹⁰²⁹. The CΔ1012 mutant, with further truncation (Gln¹⁰¹²-Phe¹⁰⁵⁰) of the carboxy terminus, did not show STa-mediated GC activation. Based on these data, these 17 amino acids (Gln¹⁰¹²-Ala¹⁰²⁸), essential for signaling of GC activation by STa, have an abundance of basic amino acids which might be functionally influenced by phosphorylation of Ser¹⁰²⁹.

【 授权许可】

Unknown