MOLECULAR-CLONING AND EXPRESSION OF A NOVEL HUMAN AQUAPORIN FROM ADIPOSE-TISSUE WITH GLYCEROL PERMEABILITY

In a systematic analysis of genes expressed in human adipose tissue, w e detected a novel gene that is expressed uniquely in adipose tissue. The sequence showed that it encodes a 342-amino-acid protein containin g six putative transmembrane domains, and is a new member of the aquap orin family of water-selective membrane channels. We named this gene a quaporin 9. It features a cyclic-AMP protein kinase phosphorylation co nsensus site in the NH3-terminal domain. Expression of the cRNA in Xen opus oocytes yielded a 7-fold increase in osmotic water permeability b locked by 0.3 mM HgCl2, and also facilitated the uptake of glycerol. N orthern blot analysis demonstrated that the mRNA is abundant in adipos e tissue, but not in other tissues. Thus, this gene product may partic ipate in glycerol transport in adipocytes. (C) 1997 Academic Press.