Chapter 20 - Reversible Histidine Phosphorylation in Mammalian Cells: A Teeter-Totter Formed by Nucleoside Diphosphate Kinase and Protein Histidine Phosphatase 1

Abstract

Regulation of protein phosphorylation by kinases and phosphatases is involved in many signaling pathways in mammalian cells. In contrast to prokaryotes and lower eukaryotes a role for the reversible phosphorylation of histidine residues is just emerging. The β subunit of heterotrimeric G proteins, the metabolic enzyme adenosine 5'-triphosphate-citrate lyase (ACL), and the Ca2+-activated K+ channel KCa3.1 have been identified as targets for nucleoside diphosphate kinase (NDPK) acting as protein histidine kinase and the so far only identified mammalian protein histidine phosphatase (PHPT-1). Herein, we describe the analysis of the phosphorylation and dephosphorylation of histidine residues by NDPK and PHPT-1. In addition, experimental protocols for studying the consequences of heterotrimeric G protein activation via NDPK/Gβγ mediated phosphorelay, the regulation of ACL activity and of KCa3.1 conductivity by histidine phosphorylation will be presented.