A novel human type I hair keratin gene: evidence for two keratin hHa3 isoforms
- 35 Downloads
We present the nucleotide and amino acid sequence for a novel human type I hair keratin, which could be identified through its high sequence homology and strict carboxyterminal length identity as a human ortholog of the murine hair keratin mHa3. Our hHa3 sequence differs, however, from that of a previously described hHa3 hair keratin (published only as an amino acid sequence; ) in 24 amino acid positions, 8 of which occur in the middle of the carboxyterminal domain. PCR of genomic DNA from 25 normal human subjects using a primer pair derived from sequence segments located in the 3′-region of our hHa3 clone that encode conserved amino acid sequences in both keratins, resulted in the amplification of two distinct products of 0.38 kbp and 1.0 kbp. DNA sequence analysis of the cloned PCR products allowed identification of the 0.38 kb sequence as that originating from Yuet al.  and the 1.0 kb sequence as that being derived from our data. The difference in fragment length was due to unique intron 6 sequences, indicating that these two keratin species are encoded by genes of their own. Moreover, extensive Southern blot analyses with DNA from 25 unrelated individuals of different races using a 3′-noncoding sequence from our keratin and the intron 6 sequence of the keratin of Yuet al. , as hybridization probes showed that both keratin genes are present as single copy sequences occurring ubiquitously and without gross alterations in the human genome. Collectively, these data demonstrate that the human type I hair keratin described in this paper represents an isoform of the previously described hHa3 keratin. We propose that these hHa3 isoforms be named in chronological order of discovery hHa3-I and hHa3-II.
Key wordshuman hair keratins Sequence homology keratin isoforms
Unable to display preview. Download preview PDF.
- 5.Powell BC & Rogers GE (1986) In: Bereiter-Hahn JE, Matoltsy AG & Richards KS (Eds) Biology of the Integument (pp 695–721) Springer-Verlag, New YorkGoogle Scholar
- 9.Bertolino AP, Checkla DM, Heitner S, Freedberg JM & Yu DW (1990) J. Invest. Dermatol. 94: 293–303Google Scholar
- 13.Yu J, Yu DW, Checkla DM, Freedberg IM & Bertolino AP (1993) J. Invest. Dermatol. 101: 565–595Google Scholar
- 14.Rogers MA, Nischt R, Korge B, Krieg T, Fink TM, Lichter P, Winter H & Schweizer J (1995) Exp. Cell. Res. (submitted).Google Scholar
- 15.Sanger F, Nicklen S & Coulson AR (1977) Proc. Natl. Acad. Sci. USA 75: 5463–5467Google Scholar
- 16.Waltering S (1994). Murine Haarkeratingene: Mutationsanalysen in Mäusestämmen mit normalem und defektem Haarkleid. Diploma Thesis, Faculty of Biology, University of HeidelbergGoogle Scholar
- 21.Takahashi K, Paladini R & Coulombe P (1994) Cloning and functional characterization of multiple type II keratin K6 isoforms in human. J. Invest. Dermatol. 102: 541Google Scholar