G-rich, a Drosophila selenoprotein, is a Golgi-resident type III membrane protein.
G-rich is a Drosophila melanogaster selenoprotein, which is a homologue of human and mouse SelK. Subcellular localization analysis using GFP-tagged G-rich showed that G-rich was localized in the Golgi apparatus. The fusion protein was co-localized with the Golgi marker proteins but not with an endoplasmic reticulum (ER) marker protein in Drosophila SL2 cells. Bioinformatic analysis of G-rich suggests that this protein is either type II or type III transmembrane protein. To determine the type of transmembrane protein experimentally, GFP-G-rich in which GFP was tagged at the N-terminus of G-rich, or G-rich-GFP in which GFP was tagged at the C-terminus of G-rich, were expressed in SL2 cells. The tagged proteins were then digested with trypsin, and analyzed by Western blot analysis. The results showed that the C-terminus of the G-rich protein was exposed to the cytoplasm indicating it is a type III microsomal membrane protein. G-rich is the first selenoprotein identified in the Golgi apparatus.
Chen
Chang Lan
CL
School of Biological Sciences and Institute of Molecular Biology and Genetics, Seoul National University, Seoul 151-742, Republic of Korea.
Shim
Myoung Sup
MS
Chung
Jiyeol
J
Yoo
Hyun-Seung
HS
Ha
Ji Min
JM
Kim
Jin Young
JY
Choi
Jinmi
J
Zang
Shu Liang
SL
Hou
Xiao
X
Carlson
Bradley A
BA
Hatfield
Dolph L
DL
Lee
Byeong Jae
BJ
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D029721:Drosophila Proteins / Q000032:analysis* / Q000737:chemistry / Q000235:genetics; D004331:Drosophila melanogaster / Q000737:chemistry* / Q000166:cytology / Q000235:genetics; D006056:Golgi Apparatus / Q000737:chemistry*; D007425:Intracellular Membranes / Q000737:chemistry; D008565:Membrane Proteins / Q000032:analysis* / Q000737:chemistry / Q000235:genetics; D008969:Molecular Sequence Data; D051140:Selenoproteins / Q000032:analysis* / Q000737:chemistry / Q000235:genetics
D029721:Drosophila Proteins; D008565:Membrane Proteins; C490437:SelG protein, Drosophila; D051140:Selenoproteins