Human platelets were extracted with acid-ethanol and platelet-derived TGF-beta was purified from the extract by a two-column procedure using sequential gel filtration in the absenceand then presence of urea. Purified TGF-beta is a protein of 25,000-daltons, and it is comprised of two 12,500-dalton subunits held together by disulfide bonds. The purified factor elicits its biological activity at concentrations less than 4pM. Comparative studies showed that platelets contain 100 times more TGF-beta than do other non-neoplastic tissues. Platelets also contain a peptide growth factor related to EGF. These two new growth factors can interact mechanistically. Incubation of TGF-beta with NRK cells for 6 h results in an increased number of cell surface EGF receptors. IGF-II receptors are not affected. Shorter incubations with TGF-beta show that this peptide can also increase the Kd of the high affinity EGF receptor.

Agency
National Institute of Health (NIH)
Institute
Division of Cancer Epidemiology And Genetics (NCI)
Type
Intramural Research (Z01)
Project #
1Z01CP005267-04
Application #
4692352
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
4
Fiscal Year
1985
Total Cost
Indirect Cost
Name
Cancer Epidemiology and Genetics
Department
Type
DUNS #
City
State
Country
United States
Zip Code