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Abe, H., Endo, T., Yamamoto, K. & Obinata, T. (1990) Sequence of cDNAs Encoding Actin Depolymerizing Factor and Cofilin of Embryonic Chicken Skeletal Muscle: Two Functionally Distinct Actin-Regulatory Proteins Exhibit High Structural Homology. Biochemistry. 29, 7420-7425. 


Two actin-regulatory proteins of 19 and 20 kDa are involved in the regulation of actin assembly in developing chicken skeletal muscle.  They are homologous with actin depolymerizing factor (ADF) and cofilin, a pH-dependent actin-modulating protein, which were originally discovered in chicken and mammalian brain respectively.  In this study, full-length cDNA clones were isolated by screening a
lgt11 cDNA library constructed from poly(A+) RNA of embryonic chicken skeletal muscle with the antibodies specific for each protein, and their complete sequences were determined.  The chicken cofilin cDNA encoded a protein of 166 amino acids, the sequence of which had over 80% identity with that of porcine brain cofilin.  The amino acid sequence of the ADF was 165 amino acids and showed about 70% identity with either chicken or mammalian cofilin, in spite of the fact that ADF and cofilin are functionally distinct.  Like chicken and mammalian cofilin, ADF and cofilin shared a hexapeptide identical with the amino-terminal sequence of tropomyosin as well as the regions homologous to other actin-regulatory proteins, including depactin, gelsolin, and profilin.  The overall nucleotide sequences and Southern blot analysis of genomic DNA, however, indicated that the two proteins were derived from different genes.

This paper appeared back to back with a paper from Jim Bamburg's group (
Adams et al, 1990 ) in which chick brain ADF was sequenced.  While both these papers were in press, the sequence of pig brain ADF was published (Moriyama et al, 1990).  At the time that this papers were written, it was generally believed that ADF was not pH sensitive and that cofilin was because of a paper that reported this .  However, it became apparent that both proteins are pH sensitive (Hayden et al, 1993; Hawkins et al, 1993) and that there are only slight differences in their activity (Yeoh et al, 2002).  The sequence similarity noted in the C terminus of chick ADF/cofilin to gelsolin, fragmin and profilin have turned out to be spurious.  The sequences reported in this paper have been deposited in GenBank under accession numbers J02915.

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