title: Molecular evolution of a polymorphic HSP40-like protein encoded in the histocompatibility locus of an invertebrate chordate.
abstract: Allorecognition, the ability to distinguish self from non-self, occurs in most organisms. Despite the ubiquity of the allorecognition process, the genetic basis for allorecognition remains unexplored in most taxa outside vertebrates and flowering plants. The allorecognition system in the colonial ascidian Botryllus schlosseri is a notable exception. We have recently identified a polymorphic gene within the fuhc locus that may play a role in allorecognition. The encoded protein, called Hsp40-L, is a Type II member of the J-protein family which usually functions as a co-chaperone with Hsp70. While many of the residues that interact with Hsp70 are conserved in Hsp40-L, it may not be a housekeeping protein because it is surprisingly polymorphic and expressed in the ampullae, the site of allorecognition. While the majority of the Hsp40-L protein appears to evolve under purifying selection, a section of the C-terminal region likely experiences balancing/directional selection, characteristic of other allorecognition proteins.
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA 93106, USA. marie.nydam@centre.edu
authors.forename: Marie L
authors.initials: ML
authors.lastname: Nydam
authors.forename: Tinya A
authors.initials: TA
authors.lastname: Hoang
authors.forename: Katie M
authors.initials: KM
authors.lastname: Shanley
authors.forename: Anthony W
authors.initials: AW
authors.lastname: De Tomaso
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D004848:Epithelium / Q000378:metabolism; D019143:Evolution, Molecular; D015870:Gene Expression; D056426:Genetic Loci / Q000235:genetics; D050956:HSP40 Heat-Shock Proteins / Q000235:genetics*; D006648:Histocompatibility / Q000235:genetics*; D017403:In Situ Hybridization; D018832:Molecular Chaperones / Q000235:genetics; D008969:Molecular Sequence Data; D011110:Polymorphism, Genetic; D017386:Sequence Homology, Amino Acid; D014561:Urochordata / Q000235:genetics*
chemical_list: D050956:HSP40 Heat-Shock Proteins; D018832:Molecular Chaperones
keywords: Allorecognition; Botryllus schlosseri; DnaJ; Hsp40; Invertebrate