Highly Cooperative Dependence of Sarco/Endoplasmic Reticulum Calcium ATPase (SERCA) 2a Pump Activity on Cytosolic Calcium in Living Cells

Abstract

Sarco/endoplasmic reticulum (SR/ER) Cadynamics. F-L577 will be useful for future studies on Ca 2؉ signaling involving SERCA2a activity. Intracellular Ca2ϩ plays a pivotal role in controlling numerous cellular processes such as exocytosis, gene transcription, cell proliferation, muscle contraction, and cell survival (1). The level of intracellular Ca 2ϩ is determined by the balance between the influx that introduces Ca 2ϩ into the cytoplasm and the efflux that removes it from the cytoplasm. The key molecules involved in the regulation of intracellular Ca 2ϩ such as channels, pumps, and exchangers have been identified (2). Channels in the plasma membrane and sarco/endoplasmic reticulum (SR/ER) 8 membrane are responsible for the Ca 2ϩ influx, whereas pumps and exchangers carry out the Ca 2ϩ efflux. SR/ER Ca 2ϩ -ATPase (SERCA) is a Ca 2ϩ pump that transfers Ca 2ϩ from the cytosol to the lumen of the SR/ER at the expense of ATP hydrolysis (3). SERCA functions to determine the resting level of intracellular Ca 2ϩ (4) and to control the spatiotemporal profile of Ca 2ϩ transients and the frequency of Ca 2ϩ oscillations (5). Impairment of SERCA causes Ca 2ϩ homeostatic dysfunction, resulting in several important disease states such as heart failure, hypertension, diabetes, and Alzheimer disease (6).The SERCA family consists of three isoforms and their splicing variants (SERCA1a, -1b, -2a, -2b, -3a, -3b, and -3c). The molecular masses of SERCA isoforms range from 105 to 115 kDa. Each SERCA isoform consists of four distinct functional domains, namely the nucleotide-binding, phosphorylation, actuator, and transmembrane domains (7). The three-dimensional structures of different conformational states of SERCA1a have been defined by x-ray crystallography (8), and structural models for the catalytic cycle of SERCA are well established (9).

Sarcoendoplasmic Reticulum Ca2+ ATPase. A Critical Target in Chlorine Inhalation–Induced Cardiotoxicity

“…Ranolazine also has been shown to indirectly stabilize SERCA in hearts of dogs with mild cardiac failure (18). SERCA plays a dynamic role in controlling cytosolic calcium content (54). Forster resident energy transfer studies of SR luminal calcium with specifically labeled SERCA2a showed that SERCA2a conformational changes directly coincided with calcium pump activity and appearance of luminal SR calcium.…”

Regulation of Cellular Communication by Signaling Microdomains in the Blood Vessel Wall

“…After stimulation of a cell, the SR is able to replenish its content by pumping calcium via the sarco/endoplasmic reticulum calcium ATPase (SERCA) pumps localized strategically in close apposition to the plasma membrane and the mitochondria (Fig. 2, E and F) (Putney, 1986;Floyd 520 and Wray, 2007;Satoh et al, 2011). Thus, the SR is able to refill its calcium stock from both the extracellular space and the mitochondria.…”

Detection of SNARE Complexes with FRET Using the Tetracysteine system

“…A comparison of the tetracysteine tag with YFP demonstrated that the insertion of the two fluorescent proteins can lead to alterations in pharmacological and signaling properties of the receptor, whereas the use of FlAsH as a FRET acceptor for CFP improved both the sensitivity of detection and the downstream signaling of the receptor (26). Similar tetracysteine-based strategies have been employed to study the activation of 2 -adrenoreceptors (2627), acetylcholine receptors (2829), endothelin receptor (30), Ca-ATPase (3132), and amyloid formation (19). …”