【Objective】Studying the MDM2/4 albuminoid encoded in the genome of Daphnia pulex will provide refe-
rences 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.