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UT-B is expressed in bovine rumen: Potential role in ruminal urea transport

Lookup NU author(s): Dr Gavin Stewart, Dr Christopher Graham, Professor Nicholas Simmons


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The UT-A (SLC14a2) and UT-B (SLC14a1) genes encode a family of specialized urea transporter proteins that regulate urea movement across plasma membranes. In this report, we describe the structure of the bovine UT-B (bUT-B) gene and characterize UT-B expression in bovine rumen. Northern analysis using a full-length bUT-B probe detected a 3.7-kb UT-B signal in rumen. RT-PCR of bovine mRNA revealed the presence of two UT-B splice variants, bUT-B1 and bUT-B2, with bUT-B2 the predominant variant in rumen. Immunoblotting studies of bovine rumen tissue, using an antibody targeted to the NH2-terminus of mouse UT-B, confirmed the presence of 43- to 54-kDa UT-B proteins. Immunolocalization studies showed that UT-B was mainly located on cell plasma membranes in epithelial layers of the bovine rumen. Using chamber measurements of ruminal transepithelial transport of 14C-labeled urea indicated that urea flux was characteristically inhibited by phloretin. We conclude that bUT-B is expressed in the bovine rumen and may function to transport urea into the rumen as part of the ruminant urea nitrogen salvaging process.

Publication metadata

Author(s): Stewart GS, Graham C, Cattell S, Smith TPL, Simmons NL, Smith CP

Publication type: Article

Publication status: Published

Journal: American Journal of Physiology - Regulatory Integrative and Comparative Physiology

Year: 2005

Volume: 289

Issue: 2

Pages: R605-R612

Print publication date: 01/08/2005

ISSN (print): 0363-6119

ISSN (electronic): 1522-1490

Publisher: American Physiological Society


DOI: 10.1152/ajpregu.00127.2005

PubMed id: 15845882


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