| Popis: |
The aim here is to investigate the relationship between sequence and structure for families of structurally related proteins with low sequence identity in order to determine any conserved positions and define them. We do this in two main ways: (i) Evolution of Three Dimensional Structures The members of the 4-helical cytokine superfamily of proteins have no significant sequence identity. Despite this superfamilies' low to non-existent sequence similarity their homology is inferred by their common structural and functions. We carry out an in depth analysis of the long and short chain families both separately and together to determine the conserved structural regions. From an examination of the residues that occur at equivalent sites within these regions we identified the only positions at which there is any conservation. We then determined the structural role of these conserved sites so as to understand how the members of this family can maintain similar structures but have very different sequences. (ii) Evolution of Sequences Within Genomes For the cadherin superfamily, we use automated methods and hand analysis (incorporating information gathered previously on the structurally important residues) in order to identify all cadherin domains in their respective proteins within two sequenced eukaryotic genomes, Caenorhabditis elegans and Drosophila melanogaster. Identification of the entire cadherin protein repertoires within the two eukaryotic genomes allowed us to carry out a comparative analysis. This allows that the cadherin repertoires in the two organisms are surprisingly different. The ability to identify all genes within an organism that encode certain structural domains is certainly a huge achievement, and must be part of the way towards understanding an organism in its entirety. |
