Anti-proSAAS serum, from rabbit

ProSAAS (UniProt: Q9QXV0; also known as IA-4, Proprotein convertase subtilisin/kexin type 1 inhibitor, Proprotein convertase 1 inhibitor, pro-SAAS) is encoded by the Pcsk1n gene (Gene ID: 30052) in murine species. ProSAAS is a small secretory protein that is primarily expressed in neural and neuroendocrine tissues and acts as an anti-aggregant chaperone. Its presence appears to be restricted only to vertebrates. Mammalian proSAAS does not undergo either glycosylation or phosphorylation, but undergoes proteolytic cleavage at several pairs of basic residues that leaves its core region intact. ProSAAS is known to interact with proprotein convertase subtilisin/kexin type 1 (PCSK1) via the C-terminal inhibitory domain (aa 219-258). In the neural tissues proSAAS exhibits neuroprotective effects and is shown to block alpha-synuclein-induced cytotoxicity in cultures of dopaminergic neurons and in SH-SY5Y cells. In vitro studies have shown that proSAAS can also prevent the fibrillation of amyloid beta 1-42 peptide in a dose-dependent manner and residues 97-180 are sufficient for its anti-aggregation function against amyloid peptides. Inclusion of recombinant proSAAS in the medium of Neuro2a cells is shown to block the neurocytotoxic effect of amyloid peptide 1-42.