Preliminary Study Of Two New Protein Domain Identification-cum-growth Differentiation Factor 3 Function

The dissertation consists of two parts: the first part describes the identification of NCD3G and CARDP, two novel protein domains; the second part describes the expression of GDF3 in brain, tumor cells and 3T3-L1, and the reconstruction of prokaryotic and eukaryotic vector for GDF3.In the first part, we identified two novel domains using bioinformatic tools. NCD3G is conserved in family 3 GPCRs, including metabotropic glutamate receptors, calcium sensing receptors, pheromone receptors and taste receptors, with the exception of GABAB receptors. Sequence analysis indicates that NCD3G domain contains nine highly conserved cysteine residues, four β strands and three disulfide bridges. Structural modeling suggests that NCD3G maybe consists of two A1 repeats and the conserved residues are related with certain familial diseases. NCD3G may play important role in the signal transduction, and it may be a target for the development of new drug candidates. CARDP is a novel domain shared by various bacterial and archael surface-, membrane-and secreted proteins with several highly conserved glycine, leucine, acidic residues and acylamino acids. Several lines of evidence suggest that the CARDP domain may have essential functions in cell-matrix adhesion and substance binding.In the second part, we analyzed the expression of GDF3 in some tissues and cell lines by RT-PCR, in situ hybridization and immunostaining on the mRNA and protein level. GDF3 is differently distributed in hippocampus CA2 and CA1 region, and it is expressed highly in Purkinje cells in cerebellum. The expression of GDF3 is upregulated in 16 liver cancer tissues, especially in the third phase of liver cancer patients. GDF3 is highly expressed in the tumor cell lines. During the differentiation of 3T3-L1, the expression of GDF3 changed significantly. Our results suggest that GDF3 may play important roles in the central nervous system, tumorogenesis and the differentiation of3T3-L1, and it needs further study. In order to obtain active GDF3, we constructed prokaryotic and eukaryotic vectors to express recombinant GDF3 in vitro, it will be helpful for the function study and application of GDF3.