Purification and characterization of a recombinant human cripto-1 protein

Masaharu Seno, Marta Desantis, Subha Kannan, Caterina Bianco, Hiroko Tada, Nancy Kim, Megumi Kosaka, William J. Gullick, Hidenori Yamada, David S. Salomon

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)


Cripto-1 (CR-1) is a novel protein that contains a modified EGF-like motif and that does not directly bind to any of the known erb B type-1 receptor tyrosine kinase receptors. To more clearly define the biological effects of CR-1 and to more adequately compare the structure-function relationships of CR-1 with other members of the EGF family of growth factors, we have expressed a modified, full-length recombinant human CR-1 protein (rhCR-1) in E. coli and have devised a procedure for the solubilization, refolding and purification of a biologically active form of this protein. We have generated the mature form of hCR-1 from computer assisted predictions of potential signal peptide cleavage sites. Expression of the modified rhCR-1 protein in E. coli was limited to the inclusion bodies. The rhCR-1 protein was found to be expressed at high levels in bacterial cells when fused to a histidine-tag sequence. Refolding of rhCR-1 was found to be difficult because of the large number of cysteine residues in the protein which results in protein aggregation. By chemically modifying the cysteine residues in the rhCR-1 protein with 3-trimethylammoniopropyl methanethiosulfonate, additional positive charges have been introduced into the protein by this disulfiding reagent. This modification facilitates solubilization of the protein when rhCR-1 is denatured. The solubilized, denatured protein was then purified by CM cation exchange and C4 reverse phase HPLC chromatography and refolded in a redox buffer. The refolded, modified rhCR-1 protein was found to be biologically active by its ability to inhibit β-casein expression, to stimulate the tyrosine phosphorylation of Shc and the activation of MAPK and by its capacity to facilitate branching growth of mouse mammary epithelial cells in type I collagen gels.

Original languageEnglish
Pages (from-to)215-229
Number of pages15
JournalGrowth Factors
Issue number3
Publication statusPublished - 1998


  • 3-trimethylammoniopropyl methanethiosulfonate
  • Cripto
  • Duct-like branching
  • MAPK activation
  • Recombinant expression
  • Refolding
  • Shc phosphorylation
  • β-casein expression

ASJC Scopus subject areas

  • Endocrinology
  • Clinical Biochemistry
  • Cell Biology


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