Identification and characteristics of MDM2/4 albuminoid and its coding genes in Daphnia pulex genome.

[Objective]Studying the MDM2/4 albuminoid encoded in the genome of Daphnia pulex will provide references for applying Daphnia pulex to biomedicine field as a model organism.[Method]MDM2/4 albuminoid and coding protein of Daphnia pulex were identified in GenBank to analyze gene structure, transcript sequence, traits and structure of coding protein using bioinformatical software.[Result]After searching coding amino acid sequence in non-redundant GenBank by BLASTp application, the putative MDM2/4 proteins encoded in genome of Daphnia pulex were identified and designated as DAPPU_mdm2_like and DAPPU_mdm4_like, respectively. The MDM2/4 genes had only 5 exons according to EST sequence. The results from BLAST querying, prediction of subcellular location, prediction of function/structure domain and homology modeling of the structure showed that they were likely to be the MDM2/4 homologue. The DAPPU_mdm2_like structure function domain contained one ZnF_RBZ domain (amino acid 135-159), one RING domain (amino acid 250-290), and another ZnF_RBZ domain overlapping with RING domain (amino acid 269-293). Amino acid 250-290 in DAPPU_mdm4_like could be a RING domain. Using double and global alignment comparison tool of Needleman-Wunsch, it was found that DAPPU_mdm4_like and DAPPU_mdm2_like shared 28.6% alignment identities and 40.4% similarity. [Conclusion]It seemed that Daphnia pulex had the differentiation of MDM2 and MDM4 similar proteins.