BM180 is a novel component of the basement membrane implicated in the regulation of tear secretion by lacrimal acinar cells. It shares partial sequence similarity with alpha-gliadin, a plant protein recognized by antibodies in some patients with Sjögren’s syndrome. BM180 exhibits electrophoretic mobilities of 180 kDa under non-reducing conditions and 60 kDa in the presence of dithiothreitol. Competitive ELISA studies indicate that BM180 has no immunological cross-reactivity with other basement membrane proteins such as laminin 1, collagen IV, entactin, fibronectin, BM-40, perlecan, or vitronectin.
