RESUMO
Thrombospondins (TSPs) are multidomain oligomers that have complex roles in cell interactions and tissue organisation. The five vertebrate TSPs comprise two subgroups, A and B, that are assembled as trimers or pentamers, respectively. An invertebrate TSP was recently discovered in Drosophila melanogaster, but there is no knowledge of the oligomerisation status or properties of this molecule. We developed by bioinformatics a new dataset containing the single TSP of Drosophila melanogaster and four other newly identified invertebrate TSPs to examine the phylogenetic relationships of TSPs. These analyses clearly indicate pentamerisation as an early attribute of TSPs. We demonstrate experimentally that D.melanogaster TSP is assembled as a pentamer, has heparin-binding activity and is a component of extracellular matrix (ECM). During embryogenesis, the TSP transcript is concentrated at muscle attachment sites and is expressed by a subset of myoblasts and in imaginal discs. These novel results establish TSPs as highly conserved ECM components in both invertebrates and vertebrates and open fresh perspectives on the conservation of structure and biological function within this family.
Assuntos
Proteínas de Drosophila/química , Proteínas de Drosophila/genética , Drosophila melanogaster/química , Drosophila melanogaster/genética , Trombospondinas/química , Trombospondinas/genética , Sequência de Aminoácidos , Animais , Sequência de Bases , Sítios de Ligação , DNA/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/embriologia , Evolução Molecular , Matriz Extracelular/metabolismo , Regulação da Expressão Gênica no Desenvolvimento , Heparina/metabolismo , Humanos , Hibridização In Situ , Dados de Sequência Molecular , Filogenia , Estrutura Quaternária de Proteína , Estrutura Terciária de Proteína , Homologia de Sequência de Aminoácidos , Trombospondinas/metabolismoRESUMO
Ten-a and Ten-m are the two Drosophila members of the newly discovered Ten-m family of dimeric type II transmembrane proteins. Here, we report complete cDNA cloning and protein expression patterns of Ten-a. The Ten-a protein, a dimeric receptor of about 500 kDa is mainly expressed on axons of the embryonic central nervous system and on muscle attachment sites.
