Amino acid sequence data on glial fibrillary acidic protein (GFA); implications for the subdivision of intermediate filaments into epithelial and non-epithelial members.
Determination of 50% of the sequence of the astrocyte-specific intermediate filament (IF) protein documents the hypervariable regions as well as parts of the coiled-coil array of glial fibrillary acidic protein (GFA). The results show that the four non-epithelial IF proteins (myogenic desmin, mesenchymal vimentin, GFA and neurofilament 68 K protein) known to form homopolymers are much more closely related than the epithelial keratins, which seem to form heteropolymers only. Of the four non-epithelial proteins, desmin and vimentin are the most closely related, since GFA has a shorter non-alpha-helical array at the amino terminus. We discuss the possibility that the non-alpha-helical terminal arrays, because of their sequence and length variability, are responsible for differences of distinct IF with respect to physical-chemical properties such as the low ionic strength-induced depolymerization into protofilaments.
D000595:Amino Acid Sequence; D000818:Animals; D005075:Biological Evolution; D003599:Cytoskeleton / Q000032:analysis; D004848:Epithelium / Q000648:ultrastructure*; D007381:Intermediate Filament Proteins / Q000235:genetics*; D013552:Swine
D007381:Intermediate Filament Proteins