Identification and expression analysis of Fc receptor‐like proteins in Japanese flounder (Paralichthys olivaceus)

Abstract

&NA; Fc receptors (FcRs) are specific to the Fc portion of immunoglobulin (Ig) molecules. Here, four Fc receptor‐like proteins, JF‐FcR‐like protein 1‐4, were identified in Japanese flounder. Their open reading frames encoded 358, 255, 519 and 441 amino acid residues, respectively. JF‐FcR‐like protein mRNAs were mainly detected in kidney and spleen of healthy fish. Injection of formalin‐killed cells (FKCs) of Edwardsiella tarda significantly increased the spleen mRNA levels of JF‐FcR‐like protein 1 but not the other JF‐FcR‐like proteins. Injection of FKC of Streptococcus iniae did not significantly affect any of the JF‐FcR‐like protein mRNAs. These findings suggest that the FcR‐like proteins have different involvements in pathogen responses.