The leukocyte common antigen (CD45) of the Pacific hagfish, Eptatretus stoutii: implications for the primordial function of CD45.
CD45, originally known as the leukocyte common antigen, is a prototypical transmembrane protein tyrosine phosphatase that plays a critical role in signal transduction through T-cell and B-cell receptors, as well as in T-cell and B-cell development. In the present study, we show that the Pacific hagfish, widely believed to lack the adaptive immune system, has CD45. The presence of CD45 in jawless fish is consistent with the recent discovery that CD45 also plays a crucial role in innate immunity via the regulation of signaling through type I and type II cytokine receptors. It is likely that CD45 was recruited to activate lymphocytes through antigen receptors encoded by rearranging genes in jawed vertebrates.
Department of Biosystems Science, School of Advanced Sciences, The Graduate University for Advanced Studies, Sokendai, Shonan Village, Hayama 240-0193, Japan.
Taeko
T
Nagata
Takashi
T
Suzuki
Yuko
Y
Ohta
Martin F
MF
Flajnik
Masanori
M
Kasahara
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019143:Evolution, Molecular; D006196:Hagfishes / Q000235:genetics* / Q000276:immunology; D006801:Humans; D017493:Leukocyte Common Antigens / Q000235:genetics* / Q000502:physiology; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid
D017493:Leukocyte Common Antigens