UPAR_LY6_2 is a family of higher eukaryotic proteins expressed in neurons. It modulates nicotinic acetylcholine receptors by selectively increasing Ca2+-influx through this ion channel [1]. The family carries an LU protein domain - about 80 amino acids long characterised by a conserved pattern of 10 cysteine residues [2]. The family is a positive feedback regulator of Wnt/beta-catenin signalling, eg for patterning of the mesoderm and neuroectoderm in zebrafish gastrulation, where Lypd6 is GPI-anchored to the plasma-membrane and interacts with the Wnt receptor Frizzled8 and the co-receptor Lrp6 [3].

1: Modulation of the Ca2+ conductance of nicotinic acetylcholine receptors by Lypd6. Darvas M, Morsch M, Racz I, Ahmadi S, Swandulla D, Zimmer A; Eur Neuropsychopharmacol. 2009;19:670-681. PMID:19403274

2: Identification and characterization of human LYPD6, a new member of the Ly-6 superfamily. Zhang Y, Lang Q, Li J, Xie F, Wan B, Yu L; Mol Biol Rep. 2010;37:2055-2062. PMID:19653121

3: Lypd6 enhances Wnt/beta-catenin signaling by promoting Lrp6 phosphorylation in raft plasma membrane domains. Ozhan G, Sezgin E, Wehner D, Pfister AS, Kuhl SJ, Kagermeier-Schenk B, Kuhl M, Schwille P, Weidinger G; Dev Cell. 2013;26:331-345. PMID:23987510