Proprotein Convertase Subtilisin/Kexin Type 1 Inhibitor (PCSK1N)

PCSK1N contains a 33-amino acid N-terminal signal sequence as well as endoprotease-processing sites. Overall sequence conservation between the human and rodent sequences is about 84%. Northern blot analysis of multiple human tissues revealed strong expression of a 1.2-kb transcript in all brain regions tested and in pancreas. Low but detectable expression was found in kidney, and no expression was found in heart, placenta, lung, liver, and skeletal muscle. Immunolocalization of rat Pcsk1n transfected into mouse pituitary corticotrophs indicated a perinuclear distribution similar to the distribution of trans-Golgi markers. Rat Pcsk1n transfected into mouse pituitary corticotrophs was secreted into the medium as a 4-kD C-terminal fragment and a 22-kD N-terminal fragment, as well as the intact 26-kD protein.