title: Evolution of key cell signaling and adhesion protein families predates animal origins.
abstract: The evolution of animals from a unicellular ancestor involved many innovations. Choanoflagellates, unicellular and colonial protozoa closely related to Metazoa, provide a potential window into early animal evolution. We have found that choanoflagellates express representatives of a surprising number of cell signaling and adhesion protein families that have not previously been isolated from nonmetazoans, including cadherins, C-type lectins, several tyrosine kinases, and tyrosine kinase signaling pathway components. Choanoflagellates have a complex and dynamic tyrosine phosphoprotein profile, and cell proliferation is selectively affected by tyrosine kinase inhibitors. The expression in choanoflagellates of proteins involved in cell interactions in Metazoa demonstrates that these proteins evolved before the origin of animals and were later co-opted for development.
authors.affiliation: Howard Hughes Medical Institute (HHMI), University of Wisconsin, 1525 Linden Drive, Madison, WI 53706, USA.
authors.forename: Nicole
authors.initials: N
authors.lastname: King
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Hittinger
authors.forename: Sean B
authors.initials: SB
authors.lastname: Carroll
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry; D005075:Biological Evolution; D015820:Cadherins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D002448:Cell Adhesion; D015815:Cell Adhesion Molecules / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D056890:Eukaryota / Q000737:chemistry / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D019143:Evolution, Molecular; D020224:Expressed Sequence Tags; D005656:Fungal Proteins / Q000737:chemistry; D037181:Lectins, C-Type / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010766:Phosphorylation; D019000:Phosphotyrosine / Q000378:metabolism; D010802:Phylogeny; D017434:Protein Structure, Tertiary; D011505:Protein-Tyrosine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D020543:Proteome; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; D015820:Cadherins; D015815:Cell Adhesion Molecules; D005656:Fungal Proteins; D037181:Lectins, C-Type; D020543:Proteome; D015800:Protozoan Proteins; D019000:Phosphotyrosine; D011505:Protein-Tyrosine Kinases