Human erythroleukemia cells adhere to fibronectin: evidence for a Mr
190,000-receptor protein
I Virtanen, J Ylanne and T Vartio
Human erythroleukemia cells (K562) adhered rapidly on fibronectin (Fn)-
coated growth substratum under serum-free conditions. The adhesion could be
quantitatively inhibited by the synthetic peptide Arg-Gly-Asp- Ser (RGDS)
and upon hemin-induced differentiation or trypsinization of the cells. Many
of the cells also displayed rapid spreading that led to a redistribution of
F-actin into spreading edges and in many cells also to a formation of
typical actin fibers attaching to the ventral aspect of the cells. The
spreading of the cells was inhibited by cytochalasin B but not by
microtubule-disrupting drugs, suggesting an active role for the
microfilament system in the spreading process. Direct overlay assay of
electrophoretically separated polypeptides with 125I-Fn showed that in K562
cells there is a major Mr 190,000 Fn-binding protein that is lost upon
differentiation. A similar overlay assay with purified plasma and cellular
Fns followed by immunostaining with anti-Fn antibodies revealed a reaction
with a similar polypeptide. The binding of Fns on the nitrocellulose sheets
could be inhibited and the bound Fn eluted by using the RGDS peptide. From
octylglucoside extracts of radioactively surface-labeled cells, distinct Mr
190,000/185,000 membrane glycoproteins bound to Fn-heptapeptide-Sepharose,
further suggesting that the Mr 190,000 polypeptide would be the Fn-receptor
of the K562 cells.
Volume 69,
Issue 2,
pp. 578-583,
02/01/1987
Copyright © 1987 by The American Society of Hematology
