title: Amino acid periodicities and their structural implications for the evolutionarily conservative central domain of some silkmoth chorion proteins.
abstract: The central domain is an evolutionarily conservative region that is invariant in length in the A and Hc-A families of silkmoth chorion proteins. This domain shows strong sixfold periodicities for various amino acid residues, such as glycine and large non-polar residues. The periodicities and their phase relationships, together with the documented prevalence of beta-sheets and beta-turns in the chorion, strongly support a secondary structure model in which short (4-residue) beta-sheet strands alternate with beta-turns, forming a compact antiparallel, probably twisted beta-sheet. This structure should be important for the establishment of higher order structure in the chorion.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D005075:Biological Evolution; D012831:Bombyx / Q000032:analysis*; D004527:Egg Proteins; D046911:Macromolecular Substances; D008954:Models, Biological; D011487:Protein Conformation
chemical_list: D004527:Egg Proteins; D046911:Macromolecular Substances; C015753:chorion proteins