title: Classification and evolutionary analysis of the basic helix-loop-helix gene family in the green anole lizard, Anolis carolinensis.
abstract: Helix-loop-helix (bHLH) proteins play essential regulatory roles in a variety of biological processes. These highly conserved proteins form a large transcription factor superfamily, and are commonly identified in large numbers within animal, plant, and fungal genomes. The bHLH domain has been well studied in many animal species, but has not yet been characterized in non-avian reptiles. In this study, we identified 102 putative bHLH genes in the genome of the green anole lizard, Anolis carolinensis. Based on phylogenetic analysis, these genes were classified into 43 families, with 43, 24, 16, 3, 10, and 3 members assigned into groups A, B, C, D, E, and F, respectively, and 3 members categorized as "orphans". Within-group evolutionary relationships inferred from the phylogenetic analysis were consistent with highly conserved patterns observed for introns and additional domains. Results from phylogenetic analysis of the H/E(spl) family suggest that genome and tandem gene duplications have contributed to this family's expansion. Our classification and evolutionary analysis has provided insights into the evolutionary diversification of animal bHLH genes, and should aid future studies on bHLH protein regulation of key growth and developmental processes.
authors.affiliation: Institute of Life Sciences, Jiangsu University, 301 Xuefu Road, Zhenjiang, 212013, People's Republic of China. akeliu@126.com
authors.forename: Ake
authors.initials: A
authors.lastname: Liu
authors.forename: Yong
authors.initials: Y
authors.lastname: Wang
authors.forename: Debao
authors.initials: D
authors.lastname: Zhang
authors.forename: Xuhua
authors.initials: X
authors.lastname: Wang
authors.forename: Huifang
authors.initials: H
authors.lastname: Song
authors.forename: Chunwang
authors.initials: C
authors.lastname: Dang
authors.forename: Qin
authors.initials: Q
authors.lastname: Yao
authors.forename: Keping
authors.initials: K
authors.lastname: Chen
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000145:classification* / Q000235:genetics*; D019295:Computational Biology / Q000379:methods; D017124:Conserved Sequence; D019143:Evolution, Molecular; D005091:Exons; D016678:Genome; D018257:Helix-Loop-Helix Motifs; D007438:Introns; D008116:Lizards / Q000235:genetics*; D051379:Mice; D005810:Multigene Family; D016366:Open Reading Frames; D010802:Phylogeny; D056510:Position-Specific Scoring Matrices
chemical_list: D051792:Basic Helix-Loop-Helix Proteins