The sequence of a type II keratin gene expressed in human skin: conservation of structure among all intermediate filament genes.
We report here the coding sequence of the gene for a 56-kDa type II keratin (designated K6b). Using a subclone specific for a unique 3' noncoding region of the encoded mRNA, we have shown that this gene is one of at least two 56-kDa keratin genes expressed in abundance in human epidermis. Segmenting the coding portion of this gene are eight introns, six of which are identically positioned with those of a distantly related type III intermediate filament gene (vimentin), and five of which are identically positioned with those of a distantly related type I gene (50-kDa keratin). These results indicate a common ancestral origin for all three classes of intermediate filament genes. All of the highly conserved intron positions are located within, but do not demarcate, the four central alpha-helical domains common to all intermediate filament polypeptides, suggesting that these genes were probably not created piecemeal by recombination-mediated linkage of separate structural domains as they presently are known.
A L
AL
Tyner
M J
MJ
Eichman
E
E
Fuchs
D000595:Amino Acid Sequence; D001483:Base Sequence; D003001:Cloning, Molecular; D005796:Genes; D006801:Humans; D007381:Intermediate Filament Proteins / Q000235:genetics*; D007633:Keratins / Q000235:genetics*; D009693:Nucleic Acid Hybridization; D010957:Plasmids; D012333:RNA, Messenger / Q000235:genetics; D012867:Skin / Q000378:metabolism*; D014158:Transcription, Genetic
D007381:Intermediate Filament Proteins; D012333:RNA, Messenger; D007633:Keratins