Identification and expression of two novel CLIP-170/Restin isoforms expressed predominantly in muscle.
CLIP-170 and Restin, microtubule-binding proteins originally cloned from human cells, are identical except for a stretch of 35 amino acids present in Restin, but missing from CLIP-170. Here we present the discovery of two novel isoforms of the CLIP-170/Restin gene in both chickens and humans. One of the new isoforms, named CLIP-170(11), contains an 11 amino acid insert instead of the 35 amino acid insert found in Restin. Eight of these 11 amino acids, including a helix-breaking proline residue, are perfectly conserved between chickens and humans. The second new isoform, named CLIP-170(11+35), contains both the 11 and 35 amino acid inserts in tandem. PCR analysis of chicken genomic DNA revealed that all four isoforms result from differential splicing of two exons in a region of the CLIP-170 gene that contains approximately 8.6 kb of intervening sequence. We found that the CLIP-170(11) and CLIP-170(11+35) are expressed preferentially in muscle tissues. Chicken and human skeletal muscle express predominantly CLIP-170(11) and to a lesser extent CLIP-170 and CLIP-170(11+35). Adult chicken cardiac and smooth muscles also express CLIP-170(11) and CLIP-170(11+35), but CLIP-170 is the predominant isoform in these muscles as it is in all other tissues except brain. The ratios of CLIP-170 isoform expression found in embryonic and adult chicken cardiac muscles reveal that isoform expression is regulated differentially in different developmental stages as well as in different tissues.
Griparic
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Molecular Biophysics Program, Florida State University, Tallahassee, FL 32306-4370, USA.
Keller
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TC
D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002642:Chick Embryo; D002645:Chickens; D017124:Conserved Sequence; D017931:DNA Primers / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D007231:Infant, Newborn; D007381:Intermediate Filament Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008869:Microtubule-Associated Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008969:Molecular Sequence Data; D024510:Muscle Development; D009132:Muscles / Q000196:embryology / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D014018:Tissue Distribution
D017931:DNA Primers; D018076:DNA, Complementary; D007381:Intermediate Filament Proteins; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; C076744:cytoplasmic linker protein 170