Rt. Timmer et al., Localization of the urea transporter UT-B protein in human and rat erythrocytes and tissues, AM J P-CELL, 281(4), 2001, pp. C1318-C1325
A new polyclonal antibody to the human erythrocyte urea transporter UT-B de
tects a broad band between 45 and 65 kDa in human erythrocytes and between
37 and 51 kDa in rat erythrocytes. In human erythrocytes, the UT-B protein
is the Kidd (Jk) antigen, and Jk(a+b+) erythrocytes express the 45- to 65-k
Da band. However, in Jk null erythrocytes [Jk(a-b-)], only a faint band at
55 kDa is detected. In kidney medulla, a broad band between 41 and 54 kDa,
as well as a larger band at 98 kDa, is detected. Human and rat kidney show
UT-B staining in nonfenestrated endothelial cells in descending vasa recta.
UT-B protein and mRNA are detected in rat brain, colon, heart, liver, lung
, and testis. When kidney medulla or liver proteins are analyzed with the u
se of a native gel, only a single protein band is detected. UT-B protein is
detected in cultured bovine endothelial cells. We conclude that UT-B prote
in is expressed in more rat tissues than previously reported, as well as in
erythrocytes.