Basic proline-rich proteins from human parotid saliva: complete covalent structures of proteins IB-1 and IB-6

Biochemistry. 1986 May 6;25(9):2387-92. doi: 10.1021/bi00357a013.


The complete amino acid sequences of two basic proline-rich proteins, IB-1 and IB-6, from human parotid saliva have been determined. Fragments for sequence analysis were obtained by enzymatic digestions. The proteins have molecular weights of 9571 (IB-1) and 11,530 (IB-6) and contain 34 and 39 mol % proline, respectively. IB-1 and IB-6 contain an identical sequence of 54 residues except for an alanine in position 52 of IB-6, where IB-1 has proline. An unusually high number of repeated sequences occurs in both molecules. IB-1 has a blocked amino-terminal residue, pyroglutamic acid, and also contains one phosphoserine residue in position 8. The relationship of these proteins to the basic proline-rich protein IB-9 [Kauffman, D., Wong, R., Bennick, A., & Keller, P. (1982) Biochemistry 21, 6558-6562] and to other salivary proline-rich proteins is discussed.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Humans
  • Molecular Weight
  • Parotid Gland / analysis*
  • Peptide Fragments / analysis
  • Peptide Hydrolases
  • Peptides / isolation & purification*
  • Proline-Rich Protein Domains
  • Saliva / analysis*
  • Salivary Proteins and Peptides / isolation & purification*


  • Peptide Fragments
  • Peptides
  • Salivary Proteins and Peptides
  • Peptide Hydrolases