Cysteine-rich regions of pig gastric mucin contain von willebrand factor and cystine knot domains at the carboxyl terminal(1).
In order to sequence the cysteine-rich regions of pig gastric mucin (PGM), we used our previously identified pig gastric mucin clone PGM-2A to screen a pig stomach cDNA library and perform rapid amplification of cDNA ends to obtain two cysteine-rich clones, PGM-2X and PGM-Z13. PGM-2X has 1071 base pairs (bp) encoding 357 amino acids containing five serine-threonine-rich 16 amino acid tandem repeats, downstream from a cysteine-rich region similar to human and mouse MUC5AC. PGM-Z13 encodes the complete 3'-terminus of PGM and is composed of 3336 bp with a 2964 bp open reading frame encoding 988 amino acids with four serine-threonine-rich tandem repeats upstream from a cysteine-rich region similar to the carboxyl terminal regions of human and rat MUC5AC and human MUC5B. This region is homologous to von Willebrand factor C and D domains involved in acid induced polymerization, and to the carboxyl terminal cystine-knot domain of various mucins, TGF-beta, vWF and norrin, which is involved in dimerization. These newly sequenced cysteine-rich regions of pig gastric mucin may be critical for its gelation and for its observed increased viscosity induced by low pH.
Turner
B S
BS
Department of Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA.
Bhaskar
K R
KR
Hadzopoulou-Cladaras
M
M
LaMont
J T
JT
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003545:Cysteine / Q000032:analysis*; D003553:Cystine / Q000032:analysis* / Q000235:genetics; D018076:DNA, Complementary / Q000737:chemistry; D004848:Epithelium / Q000737:chemistry; D005752:Gastric Mucins / Q000737:chemistry*; D005753:Gastric Mucosa / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D008969:Molecular Sequence Data; D016415:Sequence Alignment; D012694:Serine / Q000032:analysis; D013552:Swine; D020080:Tandem Repeat Sequences; D013912:Threonine / Q000032:analysis; D014841:von Willebrand Factor / Q000737:chemistry* / Q000235:genetics
D018076:DNA, Complementary; D005752:Gastric Mucins; D014841:von Willebrand Factor; D013912:Threonine; D012694:Serine; D003553:Cystine; D003545:Cysteine