PMCCPMCCPMCC

Search tips
Search criteria 

Advanced

 
Logo of jcellbiolHomeThe Rockefeller University PressEditorsContactInstructions for AuthorsThis issue
 
J Cell Biol. Jan 1, 1985; 100(1): 86–92.
PMCID: PMC2113459
A cellular binding site for the Mr 55,000 form of the human plasminogen activator, urokinase
Abstract
The secretion of plasminogen activators has been implicated in the controlled extracellular proteolysis that accompanies cell migration and tissue remodeling. We found that the human plasminogen activator urokinase (Uk) (Mr 55,000 form) binds rapidly, specifically, and with high affinity to fresh human blood monocytes and to cells of the monocyte line U937. Upon binding Mr 55,000 Uk was observed to confer high plasminogen activator activity to the cells. Binding of the enzyme did not require a functional catalytic site (located on the B chain of the protein) but did require the noncatalytic A chain of Mr 55,000 Uk, since Mr 33,000 Uk did not bind. These results demonstrate the presence of a membrane receptor for Uk on monocytes and show a hitherto unknown function for the A chain of Uk: binding of secreted enzyme to its receptor results in Uk acting as a membrane protease. This localizes plasminogen activation near the cell surface, an optimal site to facilitate cell migration.
Full Text
The Full Text of this article is available as a PDF (1.6M).
Articles from The Journal of Cell Biology are provided here courtesy of
The Rockefeller University Press