Mapping of the domain in the neuroendocrine protein 7B2 important for its helper function towards prohormone convertase PC2.

In the secretory pathway, the neuroendocrine polypeptide 7B2 transiently associates with its physiological target, the prohormone convertase PC2. The 7B2 protein carries two functional domains involved in the control of proPC2 maturation and activation, an inhibitory C-terminal region and an N-terminal domain displaying facilitative activity. Here, we show that a short segment in 7B2 (His120-Pro131) is important for its facilitative activity. Site-directed mutagenesis indicates that within this segment. Tyr130 is particularly important for the ability of 7B2 to act as a helper protein for PC2.