title: Localization and diversity of 185/333 proteins from the purple sea urchin--unexpected protein-size range and protein expression in a new coelomocyte type.
abstract: The current paradigm proposes that the innate immune systems of invertebrates are much more complex than previously thought. The highly diverse 185/333 gene family in the purple sea urchin encodes a family of closely related proteins of varying length and sequence composition. Subsets of small phagocytes and polygonal cells express 185/333 proteins with localization on the surface of the small phagocytes and within perinuclear vesicles in both cell types. In short-term cultures, coelomocytes form small aggregates that progress to syncytia that are thought to be equivalent to encapsulation in vivo. These aggregates were found to be enriched for 185/333-positive (185/333(+)) small phagocytes. In response to lipopolysaccharide challenge, coelomocytes transiently increased, including frequencies of both 185/333(+) and 185/333-negative (185/333(-)) small phagocytes and 185/333(+) polygonal cells. The 185/333 proteins were present in a broad array of sizes, most of which were larger than that predicted from the cDNAs. Recombinant 185/333 proteins expressed in bacteria and insect cells were also larger than expected, suggesting that the proteins dimerize and multimerize. The diversity of the 185/333 proteins, their expression in response to immune challenge, and their cellular localization suggests this protein family and the small phagocytes have an important immunological role in the sea urchin.
authors.affiliation: George Washington University, Department of Biological Sciences, Washington, DC 20052, USA.
authors.forename: Virginia
authors.initials: V
authors.lastname: Brockton
authors.forename: John H
authors.initials: JH
authors.lastname: Henson
authors.forename: David A
authors.initials: DA
authors.lastname: Raftos
authors.forename: Audrey J
authors.initials: AJ
authors.lastname: Majeske
authors.forename: Young-Ok
authors.initials: YO
authors.lastname: Kim
authors.forename: L Courtney
authors.initials: LC
authors.lastname: Smith
mesh_terms: D000818:Animals; D019281:Dimerization; D004926:Escherichia coli / Q000235:genetics; D015870:Gene Expression; D007113:Immunity, Innate; D008070:Lipopolysaccharides / Q000494:pharmacology; D018613:Microscopy, Confocal; D008970:Molecular Weight; D005810:Multigene Family; D010586:Phagocytes / Q000276:immunology / Q000378:metabolism; D020836:Protein Structure, Quaternary; D011506:Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D047270:Strongylocentrotus purpuratus / Q000166:cytology / Q000235:genetics / Q000276:immunology / Q000378:metabolism*
chemical_list: D008070:Lipopolysaccharides; D011506:Proteins; D011994:Recombinant Proteins