Molecular and genetic analysis of the Drosophila mas-1 (mannosidase-1) gene which encodes a glycoprotein processing alpha 1,2-mannosidase.
Glycosylation is an important mechanism for modulating the physicochemical and biological properties of proteins in a stage- and tissue-specific manner. The enzymology of this process is just beginning to be understood. Here we present the molecular analysis of mas-1 (mannosidase-1), a Drosophila gene with significant homologies to mammalian and Saccharomyces cerevisiae glycoprotein processing alpha 1,2-mannosidases. An enhancer-trap P-element inserted upstream of mas-1 leads to highly specific lacZ expression in the lobula plate giant neurons, cells that mediate the large-field optomotor response. This staining, however, seems to reflect only a small part of the complex expression pattern of the mas-1 gene: Two promoters produce alternative transcripts that show individual spatial distributions during embryonic development, including a maternal contribution. Both transcripts code for type II transmembrane proteins which differ in their N-terminal parts. Null mutants in mas-1 display defects in the embryonic PNS, in the wing, and in the adult eye. These findings illustrate that the processing of N-linked glycans plays a functional role in Drosophila development. There is, however, ample evidence for genetic and biochemical redundancy in the mannose-trimming steps of this pathway.
Kerscher
S
S
Theodor-Boveri-Institut für Biowissenschaften, Lehrstuhl Genetik, Würzburg, Germany.
Albert
S
S
Wucherpfennig
D
D
Heisenberg
M
M
Schneuwly
S
S
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D004330:Drosophila / Q000235:genetics* / Q000378:metabolism; D008361:Mannosidases / Q000096:biosynthesis / Q000235:genetics*; D008969:Molecular Sequence Data; D016415:Sequence Alignment
D008361:Mannosidases; C046090:mannosyl-oligosaccharide 1,2-alpha-mannosidase