Review: Evolution And Diversification Of Corneous Beta-Proteins, The Characteristic Epidermal Proteins Of Reptiles And Birds

December 2018 in “ Journal of Experimental Zoology Part B Molecular and Developmental Evolution ”

Karin Brigit Holthaus, Leopold Eckhart, Luisa Dalla Valle, Lorenzo Alibardi

TLDR Corneous beta-proteins evolved uniquely in reptiles and birds, forming scales, claws, beaks, and feathers.

The review discussed the evolution and diversification of corneous beta-proteins (CBPs), which are the primary epidermal proteins in reptiles and birds. Unlike intermediate filament keratins (IF-keratins) found in all amniotes, CBPs are unique to sauropsids and are encoded by genes within the epidermal differentiation complex (EDC). These proteins form the structural basis of scales, claws, beaks, and feathers in reptiles and birds. Phylogenetic analysis indicated that CBPs in lepidosaurians (lizards and snakes) and nonlepidosaurians (crocodilians, birds, and turtles) form distinct clades, which likely originated after these groups diverged in the Permian Period. The review provided a comprehensive overview of the molecular evolution of CBPs, highlighting their role in the formation of various epidermal structures in sauropsids.

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