Identification of a novel targeting sequence for regulated secretion in the serine protease inhibitor neuroserpin.

Ns (neuroserpin) is a member of the serpin (serine protease inhibitor) gene family that is primarily expressed within the central nervous system. Its principal target protease is tPA (tissue plasminogen activator), which is thought to contribute to synaptic plasticity and to be secreted in a stimulus-dependent manner. In the present study, we demonstrate in primary neuronal cultures that Ns co-localizes in LDCVs (large dense core vesicles) with the regulated secretory protein chromogranin B.