Identification of I-plastin, a human fimbrin isoform expressed in intestine and kidney.
The complete cDNA sequence of human intestine-specific plastin (I-plastin) was determined from a clone derived by PCR. It consists of a 97-bp 5' untranslated region, a 1,887-bp coding region, and a 1,655-bp 3' untranslated region. The coding region predicts a 629-residue polypeptide whose sequence displays 86, 75, and 73% identities with chicken intestine fimbrin, human T-plastin, and human L-plastin, respectively. Recombinant I-plastin cross-linked actin filaments into bundles in the absence but not in the presence of calcium. The I-plastin gene was mapped by PCR to human chromosome 3; the L- and T-plastin genes were previously mapped to chromosomes 13 and X, respectively. I-plastin mRNA was detected in the small intestine, colon, and kidneys; relatively lower levels of expression were detected in the lungs and stomach. In contrast, L-plastin expression was restricted to the spleen and other lymph node-containing organs, while T-plastin was expressed in a variety of organs, including muscle, brain, uterus, and esophagus. In contrast to the situation for the intestine, high levels of L- and T-plastin mRNAs were detected in Caco-2, a human colon-derived cell line. Immunofluorescence microscopy detected I-plastin in the brush border of the small intestine and colon. These results identify I-plastin as the human homolog of chicken intestine fimbrin and as a third plastin isoform in humans.
Lin
C S
CS
Research Institute, Palo Alto Medical Foundation, California 94301.
Shen
W
W
Chen
Z P
ZP
Tu
Y H
YH
Matsudaira
P
P
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D001483:Base Sequence; D002352:Carrier Proteins / Q000096:biosynthesis; D002645:Chickens; D002874:Chromosome Mapping; D002882:Chromosomes, Human, Pair 13; D002893:Chromosomes, Human, Pair 3; D003001:Cloning, Molecular; D003106:Colon / Q000166:cytology / Q000378:metabolism; D006224:Cricetinae; D004247:DNA / Q000235:genetics; D017931:DNA Primers; D018076:DNA, Complementary / Q000737:chemistry; D005260:Female; D005753:Gastric Mucosa / Q000378:metabolism; D006801:Humans; D006822:Hybrid Cells; D007150:Immunohistochemistry; D007413:Intestinal Mucosa / Q000378:metabolism*; D007421:Intestine, Small / Q000166:cytology / Q000378:metabolism; D007668:Kidney / Q000378:metabolism*; D008168:Lung / Q000378:metabolism; D008562:Membrane Glycoproteins / Q000096:biosynthesis* / Q000235:genetics; D008840:Microfilament Proteins; D008969:Molecular Sequence Data; D009363:Neoplasm Proteins / Q000096:biosynthesis; D009928:Organ Specificity; D010750:Phosphoproteins / Q000032:analysis / Q000096:biosynthesis* / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D051381:Rats; D017386:Sequence Homology, Amino Acid; D014960:X Chromosome
D000906:Antibodies; D002352:Carrier Proteins; D017931:DNA Primers; D018076:DNA, Complementary; D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; D009363:Neoplasm Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; C026742:plastin; D004247:DNA