Human MUC5AC mucin dimerizes in the rough endoplasmic reticulum, similarly to the MUC2 mucin.

• Biosynthetic studies on the human MUC5AC mucin were performed by immunoprecipitations with antisera recognizing only the non-O-glycosylated apomucin in the colon adenocarcinoma cell line LS 174T. Pulse-chase studies and subcellular fractionations showed that MUC5AC formed dimers in the rough endoplasmic reticulum within 15 min of the initiation of biosynthesis. No non-O-glycosylated species larger than dimers were identified. The dimerization was N-glycosylation-dependent, because tunicamycin treatment significantly lowered the rate of dimerization. When the biosynthesis of MUC5AC apomucin was compared with that of MUC2 apomucin, also produced in the LS 174T cell line, both apomucins were assembled in similar ways with respect to their rates of dimerization with and without inhibition of N-glycosylation. No heterodimerization was observed between the human MUC5AC and the MUC2 apomucins despite the extensive sequence similarities in the positions of the cysteine residues in the C-termini proposed to be involved in mucin dimerization.

Subject headings

MEDICIN OCH HÄLSOVETENSKAP  -- Medicinsk bioteknologi -- Medicinsk bioteknologi (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Medical Biotechnology -- Medical Biotechnology (hsv//eng)

Keyword

Amino Acid Sequence

Animals

Biochemistry

methods

Carcinoma

chemistry

metabolism

Colonic Neoplasms

chemistry

metabolism

Cross Reactions

Dimerization

Endoplasmic Reticulum

Rough

metabolism

Gastric Mucins

immunology

metabolism

Glycosylation

drug effects

Humans

Immune Sera

Molecular Sequence Data

Mucin 5AC

Mucin-2

Mucins

chemistry

immunology

metabolism

Rabbits

Subcellular Fractions

Tumor Cells

Cultured

Tunicamycin

pharmacology

Ultracentrifugation

Publication and Content Type

ref (subject category)

art (subject category)