The gene for a cytoplasmic intermediate filament (IF) protein of the hemichordate Saccoglossus kowalevskii; definition of the unique features of chordate IF proteins.
We have isolated full length cDNAs encoding a cytoplasmic intermediate filament (IF) protein of a priapulid (Priapulus caudatus) and of a hemichordate (Saccoglossus kowalevskii) and determined the organisation of the hemichordate gene. As expected, the priapulid protein shows the long coil 1b subdomain and the lamin tail homology segment already known for cytoplasmic IF proteins from 11 other protostomic phyla. Surprisingly, the hemichordate protein follows in domain organisation much more closely the protostomic IF proteins than the chordate IF proteins. Thus, the lack of a lamin tail homology segment together with a deletion of 42 residues in the coil 1b domain is a molecular feature restricted to the chordates. We propose that the known IF subfamilies I to IV developed by gene duplications and sequence drift after the deletion in coil 1b arose at the base of the chordate branch.
Zimek
Alexander
A
Department of Biochemistry, Max Planck Institute for Biophysical Chemistry, Am Fassberg 11, 37077 Göttingen, Germany.
Weber
Klaus
K
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002816:Chordata, Nonvertebrate / Q000235:genetics*; D003001:Cloning, Molecular; D003593:Cytoplasm / Q000378:metabolism; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D007381:Intermediate Filament Proteins / Q000235:genetics*; D008969:Molecular Sequence Data; D010802:Phylogeny; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D007381:Intermediate Filament Proteins