Subtilisin-related serine proteases in the mammalian constitutive secretory pathway.

Proteolytic cleavage is a key step in the activation of many secreted proteins. Since the identification of the prototype yeast enzyme Kex2, seven subtilisin-related serine proteases, together with a number of isoforms, have been identified in mammalian cells, five of which act within the constitutive secretory pathway. Overlapping expression patterns and substrate specificities complicate analysis but individual roles are beginning to emerge for some members of the group.