Characterization of a brain-specific nuclear LIM domain protein (FHL1B) which is an alternatively spliced variant of FHL1.
We have amplified and sequenced a novel, alternatively spliced variant of a human gene coding for the four-and-a-half LIM domain protein 1 (FHL1). This gene is located at chromosome Xq27 and the spliced variant is named FHL1B. The ORF of FHL1B cDNA codes for a LIM-only protein that possesses a zinc finger and three tandem repeats of LIM domains at the N-terminus with an active bipartite nuclear localization signal (NLS) motif and a possible RBP-J binding region at the C-terminus. FHL1B and FHL1 have the same N-terminal three-and-a-half LIM domains but different C-terminal protein sequences, due to the presence of an additional alternative exon 4b in FHL1B causing a frame-shift in the 3'coding region. RT-PCR results revealed that the expression of FHL1 is not restricted in skeletal muscle and heart, but is widely distributed in other tissues, including brain, placenta, lung, liver, kidney and pancreas, albeit as a low abundance transcript. In contrast, FHL1B is specifically expressed in brain. The C-terminal alternative region in FHL1B is sufficient to localize FHL1B in the nucleus of mammalian cell. FHL1B is probably related to neural differentiation and certain fragile X syndrome.
Lee
S M
SM
Department of Biochemistry, Chinese University of Hong Kong, Shatin, N.T., Hong Kong.
Li
H Y
HY
Ng
E K
EK
Or
S M
SM
Chan
K K
KK
Kotaka
M
M
Chim
S S
SS
Tsui
S K
SK
Waye
M M
MM
Fung
K P
KP
Lee
C Y
CY
D017398:Alternative Splicing; D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D001921:Brain / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000378:metabolism; D020869:Gene Expression Profiling; D018398:Homeodomain Proteins / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D008969:Molecular Sequence Data; D009687:Nuclear Proteins; D009928:Organ Specificity; D017421:Sequence Analysis; D013347:Subcellular Fractions; D014960:X Chromosome; D016335:Zinc Fingers
D004268:DNA-Binding Proteins; D018398:Homeodomain Proteins; D051819:Immunoglobulin J Recombination Signal Sequence-Binding Protein; D009687:Nuclear Proteins; C497570:RBPJ protein, human