Hydractinia allodeterminant alr1 resides in an immunoglobulin superfamily-like gene complex.
Allorecognition, the ability to discriminate between self and nonself, is ubiquitous among colonial metazoans and widespread among aclonal taxa. Genetic models for the study of allorecognition have been developed in the jawed vertebrates, invertebrate chordate Botryllus, and cnidarian Hydractinia. In Botryllus, two genes contribute to the histocompatibility response, FuHC and fester. In the cnidarian Hydractinia, one of the two known allorecognition loci, alr2, has been isolated, and a second linked locus, alr1, has been mapped to the same chromosomal region, called the allorecognition complex (ARC). Here we isolate alr1 by positional cloning and report it to encode a transmembrane receptor protein with two hypervariable extracellular regions similar to immunoglobulin (Ig)-like domains. Variation in the extracellular domain largely predicts fusibility within and between laboratory strains and wild-type isolates. alr1 was found embedded in a family of immunoglobulin superfamily (IgSF)-like genes, thus establishing that the ARC histocompatibility complex is an invertebrate IgSF-like gene complex.
Department of Ecology and Evolutionary Biology, Yale University, New Haven, CT 06511, USA.
Sabrina F P
SF
Rosa
Anahid E
AE
Powell
Rafael D
RD
Rosengarten
Matthew L
ML
Nicotra
Maria A
MA
Moreno
Jane
J
Grimwood
Fadi G
FG
Lakkis
Stephen L
SL
Dellaporta
Leo W
LW
Buss
D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D003063:Cnidaria / Q000235:genetics*; D007136:Immunoglobulins / Q000737:chemistry / Q000235:genetics*; D008969:Molecular Sequence Data; D010641:Phenotype; D017386:Sequence Homology, Amino Acid
D007136:Immunoglobulins