Molecular cloning and expression of ps20 growth inhibitor. A novel WAP-type "four-disulfide core" domain protein expressed in smooth muscle

J Biol Chem. 1998 Feb 20;273(8):4574-84. doi: 10.1074/jbc.273.8.4574.


We previously reported the purification of ps20 (Rowley, D. R., Dang, T. D., Larsen, M., Gerdes, M. J., McBride, L., and Lu, B. (1995) J. Biol. Chem. 270, 22058-22065), a urogenital sinus mesenchymal cell secreted protein having growth-inhibitory properties. We report here cloning of the 1.03-kilobase rat ps20 cDNA clone from the PS-1 (adult rat prostate smooth muscle) cDNA library. Partial clones were obtained by nested polymerase chain reaction with degenerate primers, and full-length ps20 cDNA clones were isolated by plaque hybridization. Sequence analysis revealed that ps20 protein contains a WAP-type "four-disulfide core" motif and is a novel member of the WAP signature protein family composed primarily of secreted serine protease inhibitors. Native ps20 immunoprecipitated from smooth muscle cells and recombinant ps20 both resolved on SDS-polyacrylamide gel electrophoresis with apparent molecular mass of 27-29 kDa under reducing conditions and 21-23 kDa under non-reducing conditions, respectively. Stable ps20-transfectant COS-7 cell lines secreted ps20 and were growth-inhibited relative to mock transfectants. In addition, COS-7 and prostate carcinoma PC-3 cells were growth-inhibited by bacterially expressed ps20. Northern analysis indicated differential expression by tissue with highest expression in the heart. Immunohistochemical localization of ps20 protein showed cell-specific expression by both visceral and vascular smooth muscle in all tissues, including the prostate gland. These results indicate ps20 is a novel growth-regulatory member of the WAP signature family expressed by smooth muscle cells.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cell Differentiation
  • Cell Division
  • Cell Line
  • Cloning, Molecular
  • DNA, Complementary
  • Disulfides / chemistry*
  • Female
  • Growth Inhibitors / chemistry
  • Growth Inhibitors / genetics*
  • Growth Inhibitors / metabolism
  • Intercellular Signaling Peptides and Proteins
  • Male
  • Molecular Sequence Data
  • Muscle, Smooth / cytology
  • Muscle, Smooth / metabolism*
  • Proteins / chemistry
  • Proteins / genetics*
  • Proteins / metabolism
  • Rats
  • Rats, Sprague-Dawley
  • Sequence Homology, Amino Acid


  • DNA, Complementary
  • Disulfides
  • Growth Inhibitors
  • Intercellular Signaling Peptides and Proteins
  • Proteins
  • Wfdc1 protein, rat

Associated data

  • GENBANK/AF037272