Characterization of novel secreted and membrane proteins isolated by the signal sequence trap method.
We recently described a method, called the signal sequence trap (SST) method, to clone cDNAs of secreted proteins and/or type I transmembrane proteins containing N-terminal signal sequences by using an epitope-tagging expression plasmid vector. In this paper we describe the summary of a large-scale screening of approximately 5900 clones of an SST cDNA library constructed from mouse bone marrow stromal cell line ST-2 cells. Of 26 positive clones obtained and sequenced, 11 clones appeared to contain authentic signal sequences. Five of the clones corresponded to the 5' ends of the cDNA of known genes containing N-terminal signal sequences. The full-length cDNA clones of the 6 other unknown clones were isolated and sequenced. One clone, termed SDF3, encoded a mouse counterpart of human pigment epithelium-derived factor. Another clone, termed SDR1, had considerable homology with basigin, a member of the immunoglobulin superfamily. A third clone, termed SDF5, had partial homology with a Drosophila tissue polarity gene frizzled (fz) and its rat homologues, fz-1 and fz-2. The other three clones had no significant homology with sequences in the databases. These results indicate that the SST method is effective and useful for the isolation of secreted and membrane proteins without knowledge of their functions.
Shirozu
M
M
Department of Medical Chemistry, Kyoto University Faculty of Medicine, Japan.
Tada
H
H
Tashiro
K
K
Nakamura
T
T
Lopez
N D
ND
Nazarea
M
M
Hamada
T
T
Sato
T
T
Nakano
T
T
Honjo
T
T
D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D030161:Avian Proteins; D051926:Basigin; D001798:Blood Proteins; D001853:Bone Marrow / Q000737:chemistry; D003001:Cloning, Molecular / Q000379:methods*; D018076:DNA, Complementary / Q000235:genetics*; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics; D051157:Frizzled Receptors; D015723:Gene Library; D006801:Humans; D008297:Male; D008562:Membrane Glycoproteins / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification* / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D051381:Rats; D043562:Receptors, G-Protein-Coupled; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013045:Species Specificity
D015703:Antigens, CD; D000951:Antigens, Neoplasm; D000954:Antigens, Surface; D030161:Avian Proteins; C497886:BSG protein, human; D001798:Blood Proteins; C102624:Bsg protein, Gallus gallus; C497887:Bsg protein, mouse; C079432:Bsg protein, rat; D018076:DNA, Complementary; D029721:Drosophila Proteins; D051157:Frizzled Receptors; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D043562:Receptors, G-Protein-Coupled; C058784:fz protein, Drosophila; D051926:Basigin