MOLECULAR GROWTH REQUIREMENTS OF SINGLE MAMMALIAN CELLS: THE ACTION OF FETUIN IN PROMOTING CELL ATTACHMENT TO GLASS

Abstract

Fetuin, which exhibits a single electrophoretic boundary at pH 8.5 and is 95% ultracentrifugally homogenous, is fully active as the factor required for attachment and stretching S3 HeLa cells on glass. The mechanism of this action of fetuin may be a reflection of its ability to inhibit tryptic digestion of outer-cell-wall proteins. Fetuin preparations obtained from fetal serum have a much higher total yield of the "stretching factor" than that obtained from normal adult human serum. The attachment activity of fetuin requires the presence of divalent cations and can be prevented completely by 10-3 versene. Mg in a concentration of 3 x 10-4 M is maximally active as the stretching cofactor. Ca is less active, while Zn, Cd, Co and Cu are ineffective.