Characterization of tissue‐specific LIM domain protein (FHL1C) which is an alternatively spliced isoform of a human LIM‐only protein (FHL1)

EKO Ng, SMY Lee, HY Li, SM Ngai… - Journal of cellular …, 2001 - Wiley Online Library
Journal of cellular biochemistry, 2001Wiley Online Library
We have cloned and characterized another alternatively spliced isoform of the human four-
and-a-half LIM domain protein 1 (FHL1), designated FHL1C. FHL1C contains a single zinc®
nger and two tandem repeats of LIM domains at the N-terminus followed by a putative RBP-J
binding region at the C-terminus. FHL1C shares the same N-terminal two-and-a-half LIM
domains with FHL1 but different C-terminal protein sequences. Due to the absence of the
exon 4 in FHL1C, there is a frame-shift in the 3H coding region. Sequence analysis …
Abstract
We have cloned and characterized another alternatively spliced isoform of the human four-and-a-half LIM domain protein 1 (FHL1), designated FHL1C. FHL1C contains a single zinc® nger and two tandem repeats of LIM domains at the N-terminus followed by a putative RBP-J binding region at the C-terminus. FHL1C shares the same N-terminal two-and-a-half LIM domains with FHL1 but different C-terminal protein sequences. Due to the absence of the exon 4 in FHL1C, there is a frame-shift in the 3H coding region. Sequence analysis indicated that FHL1C is the human homolog of murine KyoT2. The Northern blot and RT-PCR results revealed that FHL1 is widely expressed in human tissues, including skeletal muscle and heart at a high level, albeit as a relatively low abundance transcript in brain, placenta, lung, liver, kidney, pancreas, and testis. In contrast, FHL1C is speci® cally expressed in testis, skeletal muscle, and heart at a relatively low level compared with FHL1. The expression of FHL1C transcripts was also seen in aorta, left atrium, left, and right ventricles of human heart at low level. Immunoblot analysis using af® nity-puri® ed anti-FHL1C antipeptide antibodies con® rmed a 20 kDa protein of FHL1C in human skeletal muscle and heart. Unlike FHL1B, which is another FHL1 isoform recently reported by our group and localized predominantly in the nucleus [Lee et al., 1999], FHL1C is localized both in the nucleus and cytoplasm of mammalian cell. J. Cell. Biochem. 82: 1±10, 2001.
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