Inhibitory Interaction of the Plasma Membrane Na+/Ca2+ Exchangers with the 14-3-3 Proteins

Abstract

The three Na ؉ /Ca 2؉ exchanger isoforms, NCX1, NCX2, and NCX3, contain a large cytoplasmic loop that is responsible for the regulation of activity. We have used 347 residues of the loop of NCX2 as the bait in a yeast two-hybrid approach to identify proteins that could interact with the exchanger and regulate its activity. Screening of a human brain cDNA library identified the ⑀ and isoforms of the 14-3-3 protein family as interacting partners of the exchanger. The interaction was confirmed by immunoprecipitation and in vitro binding experiments. The effect of the interaction on the homeostasis of Ca 2؉ was investigated by

The Plasma Membrane Ca2+ ATPase and the Plasma Membrane Sodium Calcium Exchanger Cooperate in the Regulation of Cell Calcium

“…The large cytosolic loop interacts with several proteins: the 14-3-3 protein, phosphorylated PLM ( phospholemman, a member of a family of transport regulators, best known as modulators of Na, K-ATPase activity) and calcineurin: they all have inhibitory function on NCX activity (Katanosaka et al 2005;Pulina et al 2006;Wang et al 2006;Zhang et al 2006). Other proteins have also been shown to interact with the NCX: ankyrin (Li et al 1993), the filamentous actin network (Condrescu and Reeves 2006), caveolin 3 (in the heart) (Bossuyt et al 2002;Camors et al 2006), and caveolin 1 and 2 (in neuronal cells) (Cha et al 2004).…”

Regulation of Sodium-Calcium Exchanger Activity by Creatine Kinase under Energy-compromised Conditions

“…It has been shown that 14-3-3 protein interacts with the three NCX isoforms and inhibits NCX activity (15). In smooth muscle cells, NCX co-localizes with Na ϩ /K ϩ -ATPase in regions closed to the sarcoplasmic reticulum that store Ca 2ϩ , which suggests a connection between NCX with its associated Na ϩ /K ϩ -ATPase and Ca 2ϩ release from the sarcoplasmic reticulum (16).…”

Downregulation of urea transporter UT-A1 activity by 14-3-3 protein

“…An inhibitory effect of 14-3-3ε was also observed on NCX (24) and Ca 2ϩ -ATPase (25). However, the mechanism underlying the negative regulation by 14-3-3 is unknown.…”

“…Some membrane proteins can interact with multiple 14-3-3 isoforms. For example, NCX2 interacts with 14-3-3 ␤-, -, -, and ε-isoforms (24). At least three isoforms of 14-3-3 (, , and ) have been reported to interact with the cardiac voltage-gated Na ϩ channel Nav1.5 (1).…”

“…A number of membrane proteins, such as the CFTR (16), Na ϩ /Ca 2ϩ exchanger (NCX) (24), human ether-a-go-go-related gene (HERG) K ϩ channel (13), Ca 2ϩ -ATPase pump (25), Na ϩ /H ϩ exchanger isoform 1 (NHE1) (15), and ␣ 2 -adrenergic receptor (23), directly interact with 14-3-3 proteins. Their interactions play important roles in regulating membrane protein cell surface expression, stability, and activity.…”