β-keratin or beta-keratin (not to be confused with β-carotene) is rich in stacked β pleated sheets, in contrast to alpha-keratin, a fibrous protein rich in alpha helices. β-keratin is found in reptiles.[1][2] It adds much more rigidity to reptilian skin than alpha-keratin does to mammalian skin. β-keratin is impregnated into the stratum corneum of the reptilian skin, providing waterproofing and the prevention of desiccation. In birds, beaks, claws and feathers also contain β-keratin. The small alvarezsaurid dinosaur Shuvuuia deserti showed evidence of a featherlike skin covering. Analysis by Schweitzer et al. (1999) showed that these featherlike structures consisted of beta-keratin.[3] [edit] References - ^ Dalla Valle L, Nardi A, Belvedere P, Toni M, Alibardi L (July 2007). "Beta-keratins of differentiating epidermis of snake comprise glycine-proline-serine-rich proteins with an avian-like gene organization". Dev. Dyn. 236 (7): 1939–53. doi:10.1002/dvdy.21202. PMID 17576619. http://dx.doi.org/10.1002/dvdy.21202.
- ^ Dalla Valle L, Nardi A, Toffolo V, Niero C, Toni M, Alibardi L (February 2007). "Cloning and characterization of scale beta-keratins in the differentiating epidermis of geckoes show they are glycine-proline-serine-rich proteins with a central motif homologous to avian beta-keratins". Dev. Dyn. 236 (2): 374–88. doi:10.1002/dvdy.21022. PMID 17191254. http://dx.doi.org/10.1002/dvdy.21022.
- ^ .Schweitzer, Mary Higby, Watt, J.A., Avci, R., Knapp, L., Chiappe, L, Norell, Mark A., Marshall, M. (1999). "Beta-Keratin Specific Immunological reactivity in Feather-Like Structures of the Cretaceous Alvarezsaurid, Shuvuuia deserti Journal of Experimental Biology (Mol Dev Evol) 255:146-157
[edit] External links | Protein: scleroproteins | | | Extracellular matrix | | | | 1-12 | type I ( COL1A1, COL1A2) · type II ( COL2A1) · type III · type IV ( COL4A1, COL4A2, COL4A3, COL4A4, COL4A5, COL4A6) · type V ( COL5A1, COL5A2, COL5A3) · type VI ( COL6A1, COL6A2, COL6A3) · type VII ( COL7A1) · type VIII ( COL8A1, COL8A2) · type IX ( COL9A1, COL9A2, COL9A3) · type X ( COL10A1) · type XI ( COL11A1, COL11A2) · type XII ( COL12A1) | | | 13-29 | | | | | | | | | | | | | | | | | Other | | | | | Keratin/Cytokeratin | | | type I/chromosome 17 (10, 12, 13, 14, 15, 16, 17, 19, 20) · chromosome 12 (18) · none (21)
type II/chromosome 12 ( 1, 2A, 3, 4, 5, 6A, 6B, 7, 8, 9) | | | | type I/chromosome 17 (31, 32, 33A, 33B, 34, 35, 36, 37, 38)
type II/chromosome 12 ( 81, 82, 83, 84, 85, 86) | | | Ungrouped alpha | chromosome 17 (23, 24, 25, 26, 27, 28, 39, 40)
chromosome 12 ( 71, 72, 73, 74, 75, 76, 77, 78, 79, 80) | | | Not alpha | Beta-keratin | | | | Other | | | | | | |
