An integumentary mucin (FIM-B.1) from Xenopus laevis homologous with von Willebrand factor

Biochemistry. 1990 Jul 3;29(26):6240-4. doi: 10.1021/bi00478a018.


We present a new protein from X. laevis skin termed "frog integumentary mucin B.1" (FIM-B.1) with a general structure similar to FIM-A.1 (formerly "spasmolysin"). The central region consisting of tandem repeats of 11 amino acid residues is probably a target for extensive O-glycosylation, whereas the C-terminal cysteine-rich domain shows pronounced homology with the C1-C2 domains and the C-terminal end of von Willebrand factor. Furthermore, we describe homology with antistasin, an anticoagulant peptide from a leech. We also discuss some implications concerning the evolutionary origin of von Willebrand factor. In situ hybridization studies revealed the expression of FIM-B.1 exclusively in mucous glands of the skin. This is comparable with FIM-A.1 but is in contrast to all other physiologically active peptides, which are synthesized in granular glands.

Publication types

  • Comparative Study

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • DNA / genetics
  • Exocrine Glands / chemistry
  • Glycosylation
  • Humans
  • Invertebrate Hormones / genetics
  • Leeches / genetics
  • Leeches / metabolism
  • Molecular Sequence Data
  • Mucins / genetics*
  • Mucins / isolation & purification
  • Mucins / physiology
  • Mucus
  • Protein Processing, Post-Translational
  • Repetitive Sequences, Nucleic Acid
  • Sequence Homology, Nucleic Acid
  • Skin / chemistry
  • Xenopus Proteins
  • Xenopus laevis / genetics
  • Xenopus laevis / metabolism*
  • von Willebrand Factor / genetics*


  • Invertebrate Hormones
  • MUC19 protein, Xenopus
  • Mucins
  • Xenopus Proteins
  • von Willebrand Factor
  • antistasin
  • DNA

Associated data

  • GENBANK/J02910