. 2012 Jan 13;3:1. doi: 10.3389/fpls.2012.00001

Table 2.

Summary of the major properties and functions of selected CaCA genes.

Gene name (species)	CaCA family	Transport function	Sub-cellular location	Main function	Reference
yrbG (E. coli)	YRBG	Putative Na⁺/Ca²⁺ exchange – unconfirmed	Inner membrane	Unknown; not involved in regulating cytosolic Ca²⁺; not essential	Naseem et al. (2008)
NCX1 (human, mouse)	NCX	Na⁺/Ca²⁺ exchange; stoichiometry: 3Na⁺:1Ca²⁺	Plasma membrane	Ca²⁺ efflux from cell in heart, brain, kidney	Blaustein and Lederer (1999)
AtMHX (Arabidopsis)	NCX (MHX)	Mg²⁺/H⁺ and Zn²⁺/H⁺ exchange; electrogenic	Vacuole	Vacuolar Mg²⁺ sequestration; Mg²⁺ homeostasis	Shaul et al. (1999)
NCKX1 (bovine, human)	NCKX	K⁺-dependent Na⁺/Ca²⁺ exchange; stoichiometry: 4Na⁺:1Ca²⁺, 1K⁺	Plasma membrane	Ca²⁺ efflux in rod photoreceptor retina cells to allow light-triggered signal generation	Reilander et al. (1992), Schnetkamp (1995)
NCKX6/NCLX (human, mouse)	CCX	Na⁺/Ca²⁺ and Li⁺/Ca²⁺ exchange, K⁺-independent?	Mitochondria	Mitochondrial Ca²⁺ efflux by Na⁺/Ca²⁺ exchange	Cai and Lytton (2004b), Palty et al. (2004, 2010)
AtCCX3 (Arabidopsis)	CCX	K⁺/H⁺, Na⁺/H⁺, and Mn²⁺/H⁺ exchange	Endo-membrane	Vesicle ion uptake; K⁺ homeostasis in flower tissues	Morris et al. (2008)
chaA (E. coli)	CAX (CHAA)	Ca²⁺/H⁺, Na⁺/H⁺, and K⁺/H⁺ exchange	Inner membrane	Outward and inward cation flux; ion homeostasis	Ivey et al. (1993), Ohyama et al. (1994), Radchenko et al. (2006)
VCX1 (yeast)	CAX	Ca²⁺/H⁺ exchange; stoichiometry: 2H⁺:1Ca²⁺	Vacuole	Vacuolar Ca²⁺ loading; regulates cytosolic Ca²⁺	Cunningham and Fink (1994), Denis and Cyert (2002)
AtCAX1 (Arabidopsis)	CAX	Ca²⁺/H⁺ exchange; stoichiometry: 3H⁺:1Ca²⁺ (based on red beet studies); can also mediate Mn²⁺/H⁺ and Cd²⁺/H⁺ exchange	Vacuole	Vacuolar Ca²⁺ loading; provides Ca²⁺ tolerance; determines cellular Ca²⁺ concentration; involved in response to stress	Blackford et al. (1990), Hirschi et al. (1996), Cheng et al. (2003), Conn et al. (2011)
CrCAX1 (green microalgae)	CAX	Ca²⁺/H⁺ and Na⁺/H⁺ exchange	Vacuole (predicted)	Provides vacuolar Ca²⁺ sequestration and Ca²⁺ tolerance when expressed in yeast	Pittman et al. (2009)
DrCAX (zebra fish)	CAX	Ca²⁺/H⁺ exchange	Endo-membrane	Neural crest development	Manohar et al. (2010)