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Mucin Agarose Gel Electrophoresis: Western Blotting for High-molecular-weight Glycoproteins
09:24

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Evidence for a second peptide cleavage in the C-terminal domain of rodent intestinal mucin Muc3

Ismat A Khatri1, Rongquan Wang, Janet F Forstner

  • 1Research Institute, Department of Structural Biology and Biochemistry, The Hospital for Sick Children, and University of Toronto, Toronto, Ontario, Canada.

The Biochemical Journal
|October 24, 2003
PubMed

Insights

Rat intestinal mucin Muc3 undergoes sequential proteolytic cleavage, generating smaller fragments. This process is crucial for mucin solubilization and signaling in enterocytes.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Gastroenterology

Background:

  • Rat intestinal mucin Muc3 (rMuc3) possesses a C-terminal SEA module with a known cleavage site.
  • Previous studies identified N-terminal (30 kDa) and C-terminal (49 kDa) glycopeptides upon expression of the rMuc3 C-terminal domain.

Purpose of the Study:

  • To investigate the fate of the membrane-anchored 49 kDa fragment of rMuc3.
  • To identify further proteolytic processing of rMuc3 and its functional implications.

Main Methods:

  • Western blotting
  • Pulse-chase metabolic incubations
  • Immunoprecipitation
  • Deglycosylation using N-glycosidase F

Main Results:

  • The 49 kDa membrane-anchored fragment of rMuc3 is further cleaved, reducing its size to 30 kDa.
  • Proteolytic products were detected and identified using various biochemical techniques.

Conclusions:

  • Sequential proteolytic cleavage of rMuc3 likely facilitates its solubilization at the enterocyte apical surface.
  • These cleavage events may enhance Muc3's role in ligand-receptor interactions and signal transduction for enterocyte function.

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