Troponin I Serine 150 Phosphorylation Inhibits pH-Induced Troponin Calcium Desensitization

Abstract

double-labeled with 2-(4'-(2''-iodoacetamido)phenyl)aminonaphthalene-6sulfonic acid (IAANS) was greater at higher temperatures, i.e. 0.11, 0.25 and 0.66 log units at 21 , 30 and 45 C respectively. In cardiac skinned fibers at higher temperatures, Ca 2þ binding affinity (-log Ca50) was further increased for D145E (from pCa50 5.5550.01 at 15 C to 6.3450.02 at 30 C) than for WT (pCa50 5.3950.01 at 15 C to 5.9650.04 at 30 C), so that DpCa50 measured at different temperatures increased in a linear fashion. Maximal tension (P0) was markedly lower for D145E compared to WT at 30 C. These data indicate that D145É s instability dictates its impaired function within the physiological milieu. NIH-HL103840 (JRP)