Discussion - 2qgnA

From cloning of the human tRNA isopentenyltransferase, a C2H2 Zn finger motif is found. From the article by Anna Glovko, this motif is always found in eukaryotic organisms although there are some exceptions for Arabidopsis thaliana, C.elegans and S.pombe. It is surprising to find that this motif is present as a single copy as this motif is usually interacting with more than one zinc finger. Moreover, the common role of this motif is in protein-RNA interation but this might not be the function in eukaryotes. The article suggested that the zinc finger motif may be involved in nuclear retention signal (La Casse 1995) and stability of enzyme conformation (Chong 1995).

Generally, the zinc finger motif have conserved glycine and tryptophan residues along the protein sequence together with cystein and histidine residues at extreme ends involved in coordination with zinc. The best conserved regions found to maintain the structural integrity of the protein in C2H2 zinc fingers are the conserved aliphatic and aromatic residues

There is no literature evidence that tells us the function of the clefts. However, based on the function of the enzyme, there is a possibility that the clefts allow ribosome to bind and interact with this enzyme during translation. According to Laskowski, clefts allow us to know how the proteins are interacting with other molecules on the protein surface. Often, a large and deep cleft is usually associated with the active site of the protein. This means that the red cleft on our protein has the highest possibility of being the active site. However, this is only assumptions and other clefts that are present might be where the active site of the protein as well.