Structures of P-type Transporting ATPases and Chromosomal Locations of Their Genes.

Abstract

ABSTRACT. P-type ATPases (EiE2-ATPases) are primary active transporters which form phospho-intermediates during their catalytic cycle. They are classified into PI to P4 based on the primary structure and potential transmembrane segments. Although the classic P-type ATPasesare cation transporters, two newmembers have recently been found; one is a flippase catalyzing the flip-flop movement of aminophospholipids, but the substrate and function of the other one remain unknown. It would be interesting to determine whether the cations and aminophospholipids are transported by similar or different mechanisms. P-type ATPases are believed to have been derived from a commonancestor, and their genes are found to be distributed in various chromosomal loci. However, gene duplication events can be traced from the tandem arrangement of genes and their linkage map. Na+/K+-and H+/K+-ATPaseshave not only closely related a subunits but also similar fi subunits. Renal Na+/K+-ATPasehas an additional subunit y. Similar small polypeptides (phospholemman, Mat-8 and CHIF), which induce Cl~and K+ currents, have been found. The idea of their functional and structural coupling with P-type ATPases, especially with H+/K+-ATPase, is intriguing. Each P-type ATPase must have specific domains or sequences for its intracellular trafficking (sorting, retention and recycling). Identification of such regions and studies on the molecules playing role in their recognition mayfacilitate the unveiling of various cellular processes regulated by P-type ATPases.Prologue

Membrane Localization of Transporter Associated with Antigen Processing (TAP)-Like (ABCB9) Visualized in Vivo with a Fluorescence Protein-Fusion Technique

“…38) As shown in Fig. 5B, expression of MAT8-DR did not affect the membrane distribution of TAP2-S-GFP.…”

Interaction of Mat-8 (FXYD-3) with Na+/K+-ATPase in Colorectal Cancer Cells

“…[1][2][3]31) However, substitution of these residues with Ala did not affect the cellular distribution of the mutant Mat-8 proteins compared with the wild-type. These results suggest that membrane Cys residues do not have specific roles, for example, in disulfide bridge formation between transmembrane helices.…”

“…6B). Thus, the conserved Gly-41 residue of Mat-8 is important for association The amino acid sequences of FXYD family members 3,24) were aligned [h, human; m, mouse; p, pig; r, rat]. The FXYD motif and potential transmembrane (TM) domain are boxed.…”

Stable expression and visualization of Mat-8 (FXYD-3) tagged with a fluorescent protein in Chinese Hamster Ovary (CHO)-K1 cells

“…They are type I membrane proteins whose carboxyl-terminal regions are postulated to be in the cytoplasm (Palmer et al 1991). Each member is characterized by the distinctive conserved cysteine residues in transmembrane and cytoplasmic regions (Maeda et al 1998). …”