The surf-4 gene encodes a novel 30 kDa integral membrane protein.
The mouse surfeit locus is a tight cluster of at least six genes (surf-1 to -6), unrelated by sequence homology, whose unique organization is conserved in vertebrates. We show that the surf-4 coding sequence is conserved between mouse and human. Primary sequence analysis predicts that the mouse surf-4 protein contains seven transmembrane domains and a double lysine endoplasmic reticulum (ER) retrieval motif on the carboxyl terminus. Translation of the mouse surf-4 cDNA in vitro resulted in the production of a 30 kDa membrane protein. Salt and detergent extraction procedures showed that the surf-4 protein associated tightly with the microsomal membranes. Proteolysis protection of 14 and 3 kDa fragments indicates that the surf-4 protein contains at least two membrane spanning domains: this is consistent with the proposed topology. Addition of the c-Myc epitope into three different regions of the surf-4 protein resulted in transfectants that expressed a myc-tagged protein. Immunofluorescence analysis of the three surf-4 myc chimeras yielded a cytoplasmic staining pattern. Consistent with the presence of the ER retrieval motif, the surf-4 myc protein was not detected at the plasma membrane. A model for the proposed structure of the surf-4 protein is presented.
Reeves
J E
JE
Eukaryotic Gene Organization and Expression Laboratory, Imperial Cancer Research Fund, London, UK.
Fried
M
M
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002451:Cell Compartmentation; D002678:Chimera / Q000235:genetics; D017124:Conserved Sequence; D004721:Endoplasmic Reticulum; D000939:Epitopes; D006801:Humans; D015151:Immunoblotting; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics* / Q000302:isolation & purification; D051379:Mice; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D011487:Protein Conformation; D011817:Rabbits; D017386:Sequence Homology, Amino Acid; D012689:Sequence Homology, Nucleic Acid
D000939:Epitopes; D008565:Membrane Proteins; C094364:SURF4 protein, human