The myristoylation of the neuronal Ca2+ -sensors guanylate cyclase-activating protein 1 and 2.
Guanylate cyclase-activating proteins (GCAPs) are Ca(2+)-binding proteins with a fatty acid (mainly myristic acid) that is covalently attached at the N terminus. Myristoylated forms of GCAP were produced in E. coli by coexpression of yeast N-myristoyl-transferase. Proteins with nearly 100% degree of myristoylation were obtained after chromatography on a reversed phase column. Although proteins were denatured by this step, they could be successfully refolded. Nonmyristoylated GCAPs activated bovine photoreceptor guanylate cyclase 1 less efficiently than the myristoylated forms. Maximal activity of guanylate cyclase at low Ca(2+)-concentration decreased about twofold, when GCAPs lacked myristoylation. In addition, the x-fold activation of cyclase was lower with nonmyristoylated GCAPs. Myristoylation of GCAP-2 had no influence on the apparent affinity for photoreceptor guanylate cyclase 1, but GCAP-1 has an about sevenfold higher affinity for cyclase, when it is myristoylated. We conclude that myristoylation of GCAP-1 and GCAP-2 is important for fine tuning of guanylate cyclase activity.
Hwang
Ji Young
JY
Institut für Biologische Informationsverarbeitung 1, Forschungszentrum Jülich, Jülich D-52425, Germany.
Koch
Karl Wilhelm
KW
D000818:Animals; D002135:Calcium-Binding Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D002417:Cattle; D024202:Electrophoretic Mobility Shift Assay; D004926:Escherichia coli / Q000235:genetics; D006162:Guanylate Cyclase / Q000378:metabolism; D051604:Guanylate Cyclase-Activating Proteins; D009227:Myristic Acids / Q000378:metabolism*; D020033:Protein Isoforms / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D012374:Rod Cell Outer Segment / Q000201:enzymology
D002135:Calcium-Binding Proteins; D051604:Guanylate Cyclase-Activating Proteins; D009227:Myristic Acids; D020033:Protein Isoforms; D006162:Guanylate Cyclase