JBC, Vol. 253, Issue 1, 24-26, Jan, 1978
Activation of adenylate cyclase in cultured fibroblasts by trypsin
D. Wallach, W. Anderson and I. Pastan
Adenylate cyclase activity measured in membranes of cultured normal rat
kidney (NRK) fibroblasts was markedly increased by prior treatment of the
intact cells with trypsin. Cell population density influenced the extent of
activation observed. Trypsin treatment of sparse cells significantly
enhanced adenylate cyclase activity, whereas similar treatment of confluent
cells caused only a slight increase in adenylate cyclase activity. The
degree of activation noted after trypsin treatment also varied depending on
the adenylate cyclase function measured. Activity determined in the
presence of GTP alone showed the greatest increase after trypsin treatment.
Similar enhancement of adenylate cyclase activity of a washed cell membrane
preparation was achieved by the addition of low concentrations of trypsin
directly to the adenylate cyclase reaction mixture. The membranes of
confluent NRK fibroblasts initially exhibited higher adenylate cyclase
activity than did membranes of sparse cells. The present results suggest
that this change in adenylate cyclase activity at cell confluence is not
due to an increase in the amount of adenylate cyclase in the cell membrane
but rather to a change in membrane components that regulate its activity.
Proteolytic activation of adenylate cyclase appears to result from
degradation of cell membrane proteins that modulate the activity of this
enzyme.
CiteULike 
Complore 
Connotea 
Del.icio.us 
Digg 
Reddit 
Technorati What's this?
