Calcium pumps expression

Waldron, R. T., Short, A. D., Meadows, J. J., Ghosh, T. K. and Gill, D. L., 1994, Endoplasmic reticulum calcium pump expression and control of cell growth. J Biol Chem 269, 11927—33. 

The smooth endoplasmic reticulum calcium pumps (SERCA) found in brain were first identified in sarcoplasmic reticulum. The three isoforms of SERCA are products of separate genes SERCA-1 is expressed in fast-twitch skeletal muscle SERCA-2a in cardiac/slow-twitch muscle SERCA-2b, an alternatively spliced form, is expressed in smooth muscle and non-muscle tissues SERCA-3 is... 

Lee, W.J., Roberts-Thomson, S.J., Holman, N.A., May, F.J., Lehrbach, G.M., Monteith, G.R., 2002, Expression of plasma membrane calcium pump isoform mRNAs in breast cancer cell lines. Cell Signal 14, 1015-1022. 

Gelebart, P., Kovacs, T., Brouland, J. P., van Gorp, R., Grossmann, J., Rivard, N., Panis, Y., Martin, V., Bredoux, R., Enouf, J. and Papp, B., 2002, Expression of endomembrane calcium pumps in colon and gastric cancer cells. Induction of SERCA3 expression during differentiation. J Biol Chem 277, 26310-20. 

Calcium pumps, also termed Ca +-ATPase, are calcium channels that transport calcium from the low concentration cytoplasm to the high concentration extracellular space or ER/SR lumenal side using the energy of ATP hydrolysis. Based on their locations, calcium pumps are classified into two groups, plasma membrane Ca +-ATPase (PMCA) and sarcoplasmic reticulum Ca +-ATPase (SERCA). " Four basic isoforms of PMCA (PMCAl 4) have been identified and the other PMCA isoforms are the alternative splicing products of the basic isoforms. PMCAl and 4 are ubiquitously expressed in different tissues and PMCA2 and 3 are expressed in nerve cells. Three basic isoforms of SERCA pump and several sphcing variants have also been identified. ... 

Egan ME, Glockner-Pagel J, Ambrose C, Cahill PA, Pappoe L, Balamuth N, Cho E, Canny S, Wagner CA, Geibel J, Caplan MJ. Calcium-pump inhibitors induce functional surface expression of Delta F508-CFTR protein in cystic fibrosis epithelial cells. Nat. Med. 2002 8 485-192. 

Among the other possible cellular receptors tested, it was found that palytoxin caused K " efflux in yeast expressing a hybrid between the Na KVATPase and the H, K -ATPase, converting this enzyme into and open channel. Interestingly, subsequent studies have described palytoxin-stimu-lated cation fluxes that were blocked by vanadate but resistant to ouabain in rat colon, suggesting that the toxin was able to convert a vanadate-sensitive H K ATPase into an electrogenic cation transporter and consequently, that the pore-forming action of palytoxin was not restricted to Na, K -ATPase since it was also observed with the coloific H, KVATPase, which is related to the sodium pmnp. The toxin was also found to interfere with the sarcolemmal calcium pump in cardiac myocytes as a secondary effect. Further smdies are required to determine how palytoxin interferes with each of the P-type ATPase pmnps or if the effects of the toxin on these pumps are consequences of structural similarities between the enzymes. ... 

Lu HG, Zhong L, Chai KP et al. Intracellular Ca pool content and signaling and expression of a calcium pump are linked to virulence in Leishmania mexicana amazonensis amast otes. J Biol Chem 1997 272 9464-9473. 

Genetic evidence supports the importance of coordinated expression and distributions of a2 or a3 Na+/K+ pump isoforms with the Na+/Ca2+ exchanger (NCX) and Ca2+ pumps to function in excitable and contractile cells deletion of one copy of the a2 Na+/K+ pump gene in mice leads to increased contractile force in cardiac and skeletal muscle while deletion of one copy of the al gene leads to reduction of contractile force [25]. In rat optic nerve astrocytes, deletion of the a2 gene or ouabain treatment of cells expressing a2 leads to increased capacitative calcium entrance responses, which reflect a decreased ability to rapidly remove cytosolic Ca2+ [26]. 

The Ca -ATPase piays an essential role In the pumping of calcium out of cells, and in the control of its cytosolic concentration. In the heart, the role of the pump is minor with respect to that of the sodium-calcium exchanger, but is most probabiy predominant in skeletal and smooth muscle. The pump is encoded by four independent genes, showing different patterns of tissue-specific expression and alternative splicing of the primary transcripts. The intracellular Ca pump proteins from skeletal muscle sarcoplasmic reticulum (SR), cardiac SR and brain microsomes are similar. Thapsigargin is a potent inhibitor, also lanthanum salts inhibit the pump at most sites. 

One should be cautious, however, to extrapolate such quantitative data to all smooth muscle types or even to similar ones of other species because of the heterogeneity of smooth muscle. For instance, Stehno-Bittel and Sturek (1992) found evidence for preferential release of Ca + from the ER toward the sarcolem-ma in bovine but not in porcine coronary artery. The ER also differs between different smooth muscles in the expression of different types of calcium-buffering proteins (Raeymaekers etal., 1993) and of the regulator protein phospholamban (see Section V). Furthermore, the data of Eggermont et al. (1988) indicate that the ratio of the number of ER and PM pump proteins also varies considerably between different smooth muscle types. 

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