Topological properties of the triple gene block protein 2 of Bamboo mosaic virus.
The triple gene block protein 2 (TGBp2) of Bamboo mosaic virus (BaMV) has been proposed to be a transmembrane protein; however, its features remain unclear. Here, we used biochemical approaches to determine its topological properties. Our data reveal that TGBp2 is mainly associated with the endoplasmic reticulum membrane. The resistance of TGBp2 in proteoliposomes, prepared from both the BaMV-infected tissues and in vitro reconstitution system, to both chemical extraction and trypsin digestion confirmed that it is indeed an integral membrane protein. On the basis of the minor change in the size of the major stable TGBp2-derived tryptic fragment from the monomeric TGBp2, as well as the sensitivity of the cysteine residues at the C-terminal tail of TGBp2 to maleimide modification, we suggest that TGBp2 adopts a topology with both its short N- and C-terminal tails exposed to the outer surface of the endoplasmic reticulum. Moreover, TGBp2 is able to self-assemble as revealed by the significant increase in multimeric TGBp2 when the TGBp2-containing proteoliposomes were treated with chemical crosslinker or oxidation agent.
Hsu
Hsiu-Ting
HT
Institute of Biochemistry, National Chung-Hsing University, Taichung 40227, Taiwan, Republic of China.
Chou
Yuan-Lin
YL
Tseng
Yang-Hao
YH
Lin
Yu-Hsing
YH
Lin
Tzung-Min
TM
Lin
Na-Sheng
NS
Hsu
Yau-Heiu
YH
Chang
Ban-Yang
BY
D002462:Cell Membrane / Q000737:chemistry; D004721:Endoplasmic Reticulum / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D059828:Plant Cells; D010944:Plants / Q000821:virology; D017863:Potexvirus / Q000502:physiology*; D011510:Proteolipids / Q000737:chemistry; D014357:Trypsin / Q000378:metabolism; D014764:Viral Proteins / Q000737:chemistry* / Q000378:metabolism*
D008565:Membrane Proteins; D011510:Proteolipids; D014764:Viral Proteins; C020485:proteoliposomes; D014357:Trypsin