Peptidoglycan recognition proteins（PGRPs） are a family of pattern recognition receptors（PRRs） of the immune system,which bind and hydrolyze bacterial peptidoglycan.Here,a long type PGRP（PGRP-L） was first cloned in the lower vertebrate species Xenopus tropicalis（Xt）.The XtPGRP-L possessed a conserved genomic structure with five exons and four introns.The alignment and phylogenetic analysis indicated that XtPGRP-L might be a type of amidase-like PGRP.The 3-D model showed that XtPGRP-L possessed a conserved structure compared with the Drosophila PGRP-Lb.During embryonic development,XtPGRP-L was not expressed until the 72 h tadpole stage.In adult tissues,it was strongly expressed in the liver,lung,intestine,and stomach.Furthermore,after LPS stimulation,the expression of XtPGRP-L was up-regulated significantly in the liver,intestine and spleen,indicating that XtPGRP-L may play an important role in the innate immunity of Xenopus tropicalis.
