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- Title
Two C-Terminal Variants of NBC4, a New Member of the Sodium Bicarbonate Cotransporter Family: Cloning, Characterization, and Localization.
- Authors
Pushkin, Alexander; Abuladze, Natalia; Newman, Debra; Lee, Ivan; Xu, Gouping; Kurtz, Ira
- Abstract
We report the cloning, characterization, and chromosomal assignment of a new member of the sodium bicarbonate cotransporter (NBC) family, NBC4. The NBC4gene was mapped to chromosome 2p13 and is a new candidate gene for Alstrom syndrome. Two variants of the transporter have been isolated from human testis and heart, which differ in their C termini. NBC4a encodes a 1137-residue polypeptide and is widely expressed in various tissues, including liver, testis, and spleen. NBC4b is identical to NBC4a except that it has a 16-nucleotide insert, creating a C-terminal frame shift. NBC4b encodes a 1074-residue polypeptide and is highly expressed in heart. Amino acids 1-1046 are common to both NBC4 variants. NBC4a has two protein-interacting domains that are lacking in NBC4b: a proline-rich sequence, PPPSVIKIP (amino acids 1102-1110), and a consensus PDZ-interacting domain, SYSL (1134-1137). NBC4b lacks the stretch of charged residues present in the C terminus of NBC4a and other members of the NBC family.Unlike other members of the NBC family, both NBC4a and NBC4b have a unique glycine-rich region (amino acids 440- 469). In comparison with other members of the bicarbonate transport superfamily, NBC4a and NBC4b are most similar structurally to the electrogenic sodium bicarbonate cotransporters (NBC1).
- Subjects
SODIUM bicarbonate; SODIUM cotransport systems; SODIUM-bicarbonate cotransporters
- Publication
IUBMB Life, 2000, Vol 50, Issue 1, p21
- ISSN
1521-6543
- Publication type
Article