Calcineurin homologous protein: a multifunctional Ca2+-binding protein family

Di Sole F, Vadnagara K, Moe OW, Babich V. Calcineurin homologous protein: a multifunctional Ca2+-binding protein family. Am J Physiol Renal Physiol 303: F165-F179, 2012. First published May 17, 2012; doi:10.1152/ajprenal.00628.2011.-The calcineurin homologous protein (CHP) belongs to an evolutionarily conserved Ca2+-binding protein subfamily. The CHP subfamily is composed of CHP1, CHP2, and CHP3, which in vertebrates share significant homology at the protein level with each other and between other Ca2+-binding proteins. The CHP structure consists of two globular domains containing from one to four EF-hand structural motifs (calcium-binding regions composed of two helixes, E and F, joined by a loop), the myristoylation, and nuclear export signals. These structural features are essential for the function of the three members of the CHP subfamily. Indeed, CHP1-CHP3 have multiple and diverse essential functions, ranging from the regulation of the plasma membrane Na+/H+ exchanger protein function, to carrier vesicle trafficking and gene transcription. The diverse functions attributed to the CHP subfamily rendered an understanding of its action highly complex and often controversial. This review provides a comprehensive and organized examination of the properties and physiological roles of the CHP subfamily with a view to revealing a link between CHP diverse functions.