Keratins: Difference between revisions

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Israel Hanukoglu, Liora Ezra, Michal Harel, Angel Herraez

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 ==Primary structures of keratins==
-In humans there are 54 functional genes that code for keratins <ref>PMID:16831889</ref> <ref name="15085952">PMID:15085952</ref>. The first sequences of human keratin cDNAs revealed that there are two distinct but homologous keratin families <ref name="6186381">PMID:6186381</ref> <ref name="6191871">PMID:6191871</ref>. These two distinct types were named as Type I keratin and Type II keratin <ref name="PMID6191871" />.
+In humans there are 54 functional genes that code for keratins <ref>PMID:16831889</ref> <ref name="PMID15085952">PMID:15085952</ref>. The first sequences of human keratin cDNAs revealed that there are two distinct but homologous keratin families <ref name="PMID6186381">PMID:6186381</ref> <ref name="PMID6191871">PMID:6191871</ref>. These two distinct types were named as Type I keratin and Type II keratin <ref name="PMID6191871" />.
-Human genome sequencing revealed that type I and type II keratin genes are located in two clusters each of which includes 27 genes on chromosome 17q21 and on chromosome 12q13 respectively <ref name="15085952" /> <ref>PMID:17428470</ref>. The juxtaposed location of the genes indicate that these gene clusters evolved by a series of gene duplication events.
+Human genome sequencing revealed that type I and type II keratin genes are located in two clusters each of which includes 27 genes on chromosome 17q21 and on chromosome 12q13 respectively <ref name="PMID15085952" /> <ref>PMID:17428470</ref>. The juxtaposed location of the genes indicate that these gene clusters evolved by a series of gene duplication events.
-Determination of the sequences of type I and type keratins revealed that the two types of keratins show a central ~300 residue segment that shows ~30% homology between the two types of proteins, but the amino and carboxy terminal regions of these proteins show great diversity <ref name="6186381" />. Consistent with the initial observations, sequencing of keratins and other intermediate filament proteins showed all IF proteins have a conserved central domain and widely divergent amino and carboxy terminal regions <ref>PMID:17521629</ref>.
+Determination of the sequences of type I and type keratins revealed that the two types of keratins show a central ~300 residue segment that shows ~30% homology between the two types of proteins, but the amino and carboxy terminal regions of these proteins show great diversity <ref name="PMID6186381" />. Consistent with the initial observations, sequencing of keratins and other intermediate filament proteins showed all IF proteins have a conserved central domain and widely divergent amino and carboxy terminal regions <ref>PMID: 17521629</ref>.
-Sequencing and two dimensional gel electrophoresis of the complete family of keratins showed that the type I and type II keratins distinct differences in their size and isolelectric points <ref>PMID:19422428</ref> <ref>PMID:18461349</ref>. Type I keratins are generally smaller (average length 460 aa's), and acidic (isoelectric point 4.4-5.4), while type II keratins are longer (average length 545 aa's) and basic (isoelectric point 5-8.3). As noted, the size differences among keratins result from differences in the amino and carboxy terminals of the proteins <ref name="PMID6191871" />.
 ==Secondary structures of keratins==