Uroplakin IIIb, a urothelial differentiation marker, dimerizes with uroplakin Ib as an early step of urothelial plaque assembly

Fang Ming Deng, Feng Xia Liang, Liyu Tu, Katheryn A. Resing, Ping Hu, Mark Supino, Chih Chi Andrew Hu, Ge Zhou, Mingxiao Ding, Gert Kreibich, Tung Tien Sun

Research output: Contribution to journalArticle

82 Scopus citations

Abstract

Urothelial plaques consist of four major uroplakins (Ia, Ib, II, and III) that form two-dimensional crystals covering the apical surface of urothelium, and provide unique opportunities for studying membrane protein assembly. Here, we describe a novel 35-kD urothelial plaqueassociated glycoprotein that is closely related to uroplakin III: they have a similar overall type 1 transmembrane topology; their amino acid sequences are 34% identical; they share an extracellular juxtamembrane stretch of 19 amino acids; their exit from the ER requires their forming a heterodimer with uroplakin Ib, but not with any other uroplakins; and UPIII-knockout leads to p35 up-regulation, possibly as a compensatory mechanism. Interestingly, p35 contains a stretch of 80 amino acid residues homologous to a hypothetical human DNA mismatch repair enzyme-related protein. Human p35 gene is mapped to chromosome 7q11.23 near the telomeric duplicated region of Williams-Beuren syndrome, a developmental disorder affecting multiple organs including the urinary tract. These results indicate that p35 (uroplakin IIIb) is a urothelial differentiation product structurally and functionally related to uroplakin III, and that p35-UPIb interaction in the ER is an important early step in urothelial plaque assembly.

Original languageEnglish (US)
Pages (from-to)685-694
Number of pages10
JournalJournal of Cell Biology
Volume159
Issue number4
DOIs
StatePublished - Nov 25 2002

Keywords

  • Bladder
  • DNA mismatch repair enzyme
  • Membrane
  • Tetraspanin
  • Urothelium

ASJC Scopus subject areas

  • Cell Biology

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