| The mannose receptor family is a subgroup of the C-type lectin superfamily and they are type â… transmembrane proteins. A common functional feature of the mannose receptor family is that they are all recycled between the plasma membrane and the endosomal machinery allowing the internalization of extracellular ligands and delivery to the interior of the cell. Mannose receptor (MR) is one member of the mannose receptor family, playing a key role in host defense and provides a link between innate and adaptive immunity. In the present study, the complement MR cDNA was cloned in Megalobrama amblycephala and its expression has been analyzed.The partial of maMR was cloned by using degenerancy primer, the full length of5295bp has been cloned using RACE-PCR, which contains an open reading frame (ORF) of4302bp coding for1433aa which has a molecular weigh of163.496kDa. The deduced amino acid sequence of Megalobrama amblycephala mannose receptor (maMR) showed77%and46%identity to Danio rerio and Dicentrarchus labrax MMR1, respectively. Domain search revealed that maMR contains a cysteine-rich domain, a single FN â…¡ domain, eight CTLDs, a transmembrane domain and a short C-terminal cytoplasmic domain. Phylogenetic analysis demonstrated that maMR is clustered in a same clade with Danio rerio MMR1. RT-PCR demonstrated that the mRNA of maMR gene constitutively expressed in all organs examined of healthy fish, with the highest level in head kidney. By real-time quantitative RT-PCR analysis, maMR transcripts were up-regulated in spleen, liver, head kidney and intestine in the initial stage after stimulated by inactivated fish bacterial pathogen Aeromonas hydrophila, and in the late stage the expreesion of MR in liver and spleen were down-regulated while maximizing in intestine.The present study was the first time to clone MR from Megalobrama amblycephala and has preliminary analysis about its expression, which may lay a foundation for the further research of biological function in fishes. |
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