Journal of Epithelial Biology & Pharmacology

2008, 1 : 35-39
Published online 2008 June 30. DOI: 10.2174/1875044300801010035
Publisher ID: JEBP-1-35

Activation and Inactivation Mechanisms of Na-HCO3 Cotransporter NBC1

George Seki , Hideomi Yamada , Shoko Horita , Masashi Suzuki , Takashi Sekine , Takashi Igarashi and Toshiro Fujita
Department of Internal Medicine, Faculty of Medicine, The University of Tokyo, 7-3-1 Hongo, Bunkyoku, Tokyo 113-0033, Japan.

ABSTRACT

The electrogenic Na+-HCO3 - cotransporter NBC1, also known as NBCe1, is expressed in several tissues such as kidney, pancreas, eye, and brain. NBC1 has three variants, which may mediate different physiological functions. Inactivating mutations in NBC1 result in proximal renal tubular acidosis associated with ocular abnormalities. Functional analysis suggests that at least 50% reduction in NBC1 activity is required to induce severe acidemia invariably associated with stunted growth. Some mutations in the NBC1 gene may also induce trafficking abnormalities. On the other hand, the variant-specific N-terminal regions seem to play an essential role in the full activation of NBC1. This review will focus on the recent progress in physiology and pathophysiology of NBC1.

Keywords:

NBC1, SLC4A4, pRTA.