A new member of the LIM protein family binds to filamin B and localizes at stress fibers.
Human filamins are 280-kDa proteins containing an N-terminal actin-binding domain followed by 24 characteristic repeats. They also interact with a number of other cellular proteins. All of those identified to date, with the exception of actin, bind to the C-terminal third of a filamin. In a yeast two-hybrid search of a human placental library, using as bait repeats 10-18 of filamin B, we isolated a cDNA coding for a novel 374 amino acid protein containing a proline-rich domain near its N terminus and two LIM domains at its C terminus. We term this protein filamin-binding LIM protein-1, FBLP-1. Yeast two-hybrid studies with deletion mutants localized the areas of interaction in FBLP-1 to its N-terminal domain and in filamin B to repeats 10-13. FBLP-1 mRNA was detected in a variety of tissues and cells including platelets and endothelial cells. We also have identified two FBLP-1 variants. Both contain three C-terminal LIM domains, but one lacks the N-terminal proline-rich domain. Transfection of FBLP-1 into 293A cells promoted stress fiber formation, and both FBLP-1 and filamin B localized to stress fibers in the transfected cells. The association between filamin B and FBLP-1 may play a hitherto unknown role in cytoskeletal function, cell adhesion, and cell motility.
Takafuta
Toshiro
T
Department of Medicine, Cardeza Foundation for Hematologic Research, Jefferson Medical College, Philadelphia, Pennsylvania 19041, USA.
Saeki
Mari
M
Fujimoto
Tetsuro-Takahiro
TT
Fujimura
Kingo
K
Shapiro
Sandor S
SS
D000199:Actins / Q000378:metabolism; D000595:Amino Acid Sequence; D001483:Base Sequence; D015815:Cell Adhesion Molecules; D003285:Contractile Proteins / Q000737:chemistry / Q000378:metabolism*; D003598:Cytoskeletal Proteins; D064448:Filamins; D017353:Gene Deletion; D015870:Gene Expression; D006801:Humans; D008840:Microfilament Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000032:analysis; D022502:Stress Fibers / Q000378:metabolism*; D020798:Two-Hybrid System Techniques; D015003:Yeasts
D000199:Actins; D015815:Cell Adhesion Molecules; D003285:Contractile Proteins; D003598:Cytoskeletal Proteins; C473794:FBLIM1 protein, human; D064448:Filamins; D008840:Microfilament Proteins; D012333:RNA, Messenger