Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A gene family of small membrane proteins, represented by phospholemman and the gamma subunit of Na,K-ATPase, was defined and characterized by the analysis of more than 1000 related ESTs (expressed sequence tags). In addition to new and more complete cDNA sequence for known family members (including MAT-8, CHIF, and RIC), the findings included two new family members and new splicing variants. A large number of EST replicates made it possible to derive curated DNA sequence with higher confidence and accuracy than from the sequencing of individual clones. The family has a core motif of 35 invariant and conserved amino acids centered on a single transmembrane span. Features of each predicted protein product were compared, and tissue distributions were determined. The gene family was named FXYD (pronounced fix-id) in recognition of invariant amino acids in its signature motif. The abundant proteins are involved in the control of ion transport.
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PMID:The FXYD gene family of small ion transport regulators or channels: cDNA sequence, protein signature sequence, and expression. 1095 Sep 25

The Na,K-ATPase is an ion pump present in the plasma membrane. It is of vital importance for cell and body homeostasis and as such is under strict hormonal control. The molecular basis for the acute regulation of Na,K-ATPase is multisite phosphorylation by protein kinases that can alter its behavior. This includes direct effects on the Na,K-ATPase activity, regulation by membrane trafficking, and even dynamic regulation of interaction with regulatory proteins. In shark Na,K-ATPase, the latter includes functional interaction with a small hydrophobic protein of the FXYD protein family, phospholemman-like protein from shark, PLMS. This article summarizes our recent work on the mechanisms involved in the acute regulation of the Na,K-ATPase studied using a plasma membrane preparation from shark salt glands as an epithelial transport model.
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PMID:Themes in ion pump regulation. 1276 92

In Na,K-ATPase membrane preparations from shark rectal glands, we have previously identified an FXYD domain-containing protein, phospholemman-like protein from shark, PLMS. This protein was shown to associate and modulate shark Na,K-ATPase activity in vitro. Here we describe the complete coding sequence, expression, and cellular localization of PLMS in the rectal gland of the shark Squalus acanthias. The mature protein contained 74 amino acids, including the N-terminal FXYD motif and a C-terminal protein kinase multisite phosphorylation motif. The sequence is preceded by a 20 amino acid candidate cleavable signal sequence. Immunogold labeling of the Na,K-ATPase alpha-subunit and PLMS showed the presence of alpha and PLMS in the basolateral membranes of the rectal gland cells and suggested their partial colocalization. Furthermore, through controlled proteolysis, the C terminus of PLMS containing the protein kinase phosphorylation domain can be specifically cleaved. Removal of this domain resulted in stimulation of maximal Na,K-ATPase activity, as well as several partial reactions. Both the E1 approximately P --> E2-P reaction, which is partially rate-limiting in shark, and the K+ deocclusion reaction, E2(K) --> E1, are accelerated. The latter may explain the finding that the apparent Na+ affinity was increased by the specific C-terminal PLMS truncation. Thus, these data are consistent with a model where interaction of the phosphorylation domain of PLMS with the Na,K-ATPase alpha-subunit is important for the modulation of shark Na,K-ATPase activity.
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PMID:Regulation of Na,K-ATPase by PLMS, the phospholemman-like protein from shark: molecular cloning, sequence, expression, cellular distribution, and functional effects of PLMS. 1287 84