Binds and may modulate the functional properties of nicotinic and muscarinic acetylcholine receptors. May regulate keratinocytes proliferation, differentiation and apoptosis. In vitro moderately inhibits ACh-evoked currents of alpha-3:beta-2-containing nAChRs and strongly these of alpha-4:beta-2-containing nAChRs, modulates alpha-7-containing nAChRs, and inhibits nicotine-induced signaling probably implicating alpha-3:beta-4-containing nAChRs. Proposed to act on alpha-3:beta-2 and alpha-7 nAChRs in an orthosteric, and on mAChRs, such as CHRM1 and CHRM3, in an allosteric manner.
Subcellular locations: Secreted
Expressed at highest levels in cervix and esophagus, followed by adult and fetal skin. Expressed at lower levels in brain, lung, stomach, small intestine, colon, rectum, uterus, and thymus. Not detected in spleen nor bone marrow. Up-regulated 3-fold in psoriatic lesional skin . In the epidermis, predominantly produced by keratinocytes of the suprabasal epidermal compartment (at protein level) . In attached gingiva, produced at highest levels by basal cells located in the lowermost epithelial layers (at protein level) . Detected in serum (at protein level) .