Correlation between a specific molecular weight form of plasminogen activator and metabolic activity of 3T3 cells.

Abstract

In quiescent cultures of [mouse fibroblast] 3T3 cells, plasminogen activator (PA) is found predominantly as a 75,000 dalton species. When quiescent cells are exposed to mitogenic agents such as phorbol myristate acetate, Ca2+, or 25% serum, the absolute levels of PA in cell lysates may either increase or decrease. A consistent observation is that in the stimulated cultures PA is found predominantly as a 49,000 dalton species. This also is the predominant form of PA in growing and transformed cells. Concomitant with the mitogen-induced stimulation of the 49,000 dalton PA in quiescent cultures is a change in morphology to one that is characteristic of growing and transformed cells. Apparently PA is not operative in causing the morphological change that occurs with activation; the 49,000 dalton PA in particular is closely related to the pleiotypic response accompanying growth stimulation and transformation.