Posttranslational processing and differential glycosylation of Tractin, an Ig-superfamily member involved in regulation of axonal outgrowth

Chunfa Jie, Yingzhi Xu, Dong Wang, Dana Lukin, Birgit Zipser, John Jellies, Kristen M. Johansen, Jørgen Johansen

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Tractin is a novel member of the Ig-superfamily which has a highly unusual structure. It contains six Ig domains, four FNIII-like domains, an acidic domain, 12 repeats of a novel proline- and glycine-rich motif with sequence similarity to collagen, a transmembrane domain, and an intracellular tail with an ankyrin and a PDZ domain binding motif. By generating domain-specific antibodies, we show that Tractin is proteolytically processed at two cleavage sites, one located in the third FNIII domain, and a second located just proximal to the transmembrane domain resulting in the formation of four fragments. The most NH2-terminal fragment which is glycosylated with the Lan3-2, Lan4-2, and Laz2-369 glycoepitopes is secreted, and we present evidence which supports a model in which the remaining fragments combine to form a secreted homodimer as well as a transmembrane heterodimer. The extracellular domain of the dimers is mostly made up of the collagen-like PG/YG-repeat domain but also contains 11/2 FNIII domain and the acidic domain. The collagen-like PG/YG-repeat domain could be selectively digested by collagenase and we show by yeast two-hybrid analysis that the intracellular domain of Tractin can interact with ankyrin. Thus, the transmembrane heterodimer of Tractin constitutes a novel protein domain configuration where sequence that has properties similar to that of extracellular matrix molecules is directly linked to the cytoskeleton through interactions with ankyrin. Copyright (C) 2000 Elsevier Science B.V.

Original languageEnglish (US)
Pages (from-to)1-14
Number of pages14
JournalBiochimica et Biophysica Acta - Protein Structure and Molecular Enzymology
Issue number1-2
StatePublished - Jun 15 2000
Externally publishedYes


  • Axonal outgrowth
  • Differential glycosylation
  • Immunoglobulin superfamily
  • Leech
  • Proteolytic processing
  • Transmembrane collagen

ASJC Scopus subject areas

  • Biophysics
  • Structural Biology
  • Biochemistry
  • Molecular Biology


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