The binding of VIP36 and α-amylase in the secretory vesicles via high-mannose type glycans

Abstract

Vesicular integral protein of 36 kDa (VIP36) is an intracellular lectin recognizing high-mannose type glycans and is highly expressed in salivary glands, especially the parotid gland, which secretes α -amylase in large quantities. Here immunoelectron microscopy demonstrated that VIP36 was primarily localized to secretory vesicles in the glandula parotis of the rat, where α-amylase also resided. A secretory vesicle fraction, prepared by Percoll density gradient centrifugation, contained both VIP36 and α-amylase. Moreover, α-amylase that was localized to these secretory vesicles contained high-mannose type glycans. In addition, VIP36 coprecipitated with α-amylase in an endo H treatment-sensitive manner. These results suggest that VIP36 is involved in the secretion of α-amylase in the rat parotid gland. © Oxford University Press 2004; all rights reserved.