Identification of splicing variants of Frabin with partly different functions and tissue distribution.
Frabin is a GDP/GTP exchange protein for Cdc42 small G protein with actin filament-binding activity. Frabin consists of the actin filament-binding domain, the Dbl homology domain, the first pleckstrin homology domain, the FYVE-finger domain, and the second pleckstrin homology domain in this order from the N-terminus. Frabin forms filopodia through direct activation of Cdc42 and lamellipodia through indirect activation of Rac small G protein. We isolated here two smaller splicing variants of frabin and named the original one, middle-size one, and smallest one frabin-alpha, -beta, and -gamma, respectively. Frabin-beta lacked the second pleckstrin homology domain and frabin-gamma lacked the FYVE-finger domain and the second pleckstrin homology domain. These three variants were expressed in all of the tissues examined but their expression levels are different depending on tissues. In L fibroblasts, all the three variants formed filopodia. As to lamellipodia, frabin-alpha formed them; frabin-beta formed them to a small extent; and frabin-gamma did not. In MDCK epithelial cells, frabin-alpha formed microspikes but frabin-beta or -gamma did not.
Ikeda
W
W
Department of Molecular Biology and Biochemistry, Osaka University Graduate School of Medicine/Faculty of Medicine, Suita, 565-0871, Japan.
Nakanishi
H
H
Takekuni
K
K
Itoh
S
S
Takai
Y
Y
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D019556:COS Cells; D002460:Cell Line; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000378:metabolism; D004285:Dogs; D004789:Enzyme Activation; D004847:Epithelial Cells / Q000378:metabolism; D005347:Fibroblasts / Q000378:metabolism; D051379:Mice; D008840:Microfilament Proteins / Q000737:chemistry*; D008957:Models, Genetic; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D014162:Transfection; D020764:cdc42 GTP-Binding Protein / Q000737:chemistry
D018076:DNA, Complementary; C485164:FGD4 protein, human; C485165:Fgd4 protein, mouse; D008840:Microfilament Proteins; D020764:cdc42 GTP-Binding Protein