Pattern Formation on Cardiac Troponin I by Consecutive Phosphorylation and Dephosphorylation

Abstract

Two serine residues located adjacently in the heart‐specific N‐terminus of cardiac troponin I can be phosphorylated in vivo. Both residues are sequentially phosphorylated and dephosphorylated by cAMP‐dependent protein kinase (PKA) and protein phosphatase 2A (PP2A). The concentration changes of the different troponin I species have been determined separately for the phosphorylation and dephosphorylation reaction and approximated by time courses predicted by a reaction model. Dependent on the concentration ratio of active protein kinase/protein phosphatase, four different troponin I species can be generated; one nonphosphorylated, two monophosphorylated and one bisphosphorylated. This pattern generation will be observed in proteins phosphorylated and dephosphorylated by a single protein kinase and phosphatase on more than one site and is a new principle inherent in signal cascades. Copyright © 1995, Wiley Blackwell. All rights reserved