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Titolo:
Functional role of polar amino acid residues in Na+/H+ exchangers
Autore:
Wiebe, CA; DiBattista, ER; Fliegel, L;
Indirizzi:
Univ Alberta, Fac Med, Dept Biochem, Edmonton, AB T6G 2H7, Canada Univ Alberta Edmonton AB Canada T6G 2H7 hem, Edmonton, AB T6G 2H7, Canada
Titolo Testata:
BIOCHEMICAL JOURNAL
, volume: 357, anno: 2001,
parte:, 1
pagine: 1 - 10
SICI:
0264-6021(20010701)357:<1:FROPAA>2.0.ZU;2-A
Fonte:
ISI
Lingua:
ENG
Soggetto:
TETRACYCLINE H+ ANTIPORTER; SITE-DIRECTED MUTAGENESIS; UNCOUPLING PROTEIN UCP-1; ESCHERICHIA-COLI; CYTOPLASMIC DOMAIN; HISTIDINE-RESIDUES; MOLECULAR-CLONING; PH-SENSOR; VIBRIO-ALGINOLYTICUS; MEMBRANE-VESICLES;
Keywords:
cation co-ordination; charge relay system; membrane protein; pH regulation; salt tolerance;
Tipo documento:
Review
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
84
Recensione:
Indirizzi per estratti:
Indirizzo: Fliegel, L Univ Alberta, Fac Med, Dept Biochem, 347 Med Sci Bldg, Edmonton, AB T6G 2H7, Canada Univ Alberta 347 Med Sci Bldg Edmonton AB Canada T6G 2H7 Canada
Citazione:
C.A. Wiebe et al., "Functional role of polar amino acid residues in Na+/H+ exchangers", BIOCHEM J, 357, 2001, pp. 1-10

Abstract

Na+/H+ exchangers are a family of ubiquitous membrane proteins. In higher eukaryotes they regulate cytosolic pH by removing an intracellular H+ in exchange for an extracellular Na+. In yeast and Escherichia coli, Na+/H+ exchangers function in the opposite direction to remove intracellular Na+ in exchange for extracellular H+. Na+/H+ exchangers display an internal pH-sensitivity that varies with the different antiporter types. Only recently have investigations examined the amino acids involved in pH-sensitivity and in cation binding and transport. Histidine residues are good candidates for H+-sensing amino acids, since they can ionize within the physiological pH range. Histidine residues have been shown to be important in the function of the: E. coli Na+/H+ exchanger NhaA and in the yeast Na+/H+ exchanger sod2. InE. coli, His(225) of NhaA may function to interact with, or regulate, the pH-sensory region of NhaA. In sod2, His(367) is also critical to transport and may be a functional analogue of His(225) of NhaA. Histidine residues are not critical for the function of the mammalian Na+/H+ exchanger, althoughan unusual histidine-rich sequence of the C-terminal tail has some influence on activity. Other amino acids involved in cation binding and transport by Na+/H+ exchangers are only beginning to be studied. Amino acids with polar side chains such as aspartate and glutamate have been implicated in transport activity of NhaA and sod2, but have not been studied in the mammalianNa+/H+ exchanger. Further studies are needed to elucidate the mechanisms involved in pH-sensitivity and cation binding and transport by Na+/H+ exchangers.

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Documento generato il 04/04/20 alle ore 09:13:43