Identification and biological characterization of an epidermal growth factor-related protein: Cripto-1

Ralf Brandt, Nicola Normanno, William J. Gullick, Jiing Huey Lin, Richard Harkins, Douglas Schneider, Brenda Wallace Jones, Fortunato Ciardiello, Maria G. Persico, Franca Armenante, Nancy Kim, David S. Salomon

Research output: Contribution to journalArticlepeer-review


The human and mouse cripto-1 (CR-1) genes can code for proteins related in structure to epidermal growth factor (EGF). A specific 36-kDa immunoreactive protein was detected by Western blot analysis in human cell lines that express CR-1 mRNA but not in cell lines that fail to express this transcript. Immunoprecipitation of GEO colon carcinoma or mouse embryonal carcinoma cells detected 27-29-kDa and 24-kDa proteins, respectively. Cell lysates and conditioned medium that were prepared from several CHO clones and were expressing either a recombinant human or mouse CR-1 cDNA contained immunospecific 27-29-kDa and 24-kDa proteins, respectively. Monensin or tunicamycin treatment resulted in a shift of the 27-29-kDa human CR-1 protein to 24 kDa and 20 kDa, respectively. The 20-kDa protein was also observed after digestion of the 27-29-kDa human CR-1 protein with N-glycosidase F. Using two CR-1 synthetic refolded peptides that correspond to the EGF-like domain of the human CR-1 sequence or conditioned medium obtained from human CR-1 expressing CHO cells, growth stimulatory activity could be detected on non-transformed human mammary epithelial cells and on two human breast cancer cell lines. EGF receptor-blocking antibody did not inhibit the growth stimulatory action of the CR-1 protein. Likewise, the CR-1 refolded peptides or conditioned medium from the human CR-1-expressing CHO cells failed to inhibit the binding of 125I-EGF in an EGF-radioreceptor assay. These data demonstrate that the CR-1 is a glycoprotein that can function as a growth factor through an EGF receptor-independent pathway.

Original languageEnglish
Pages (from-to)17320-17328
Number of pages9
JournalJournal of Biological Chemistry
Issue number25
Publication statusPublished - Jun 24 1994

ASJC Scopus subject areas

  • Biochemistry


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