Telomerase: Difference between revisions
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== Active Site Chemistry == | == Active Site Chemistry == | ||
The <scene name='60/602706/Active_site_interactions/3'>nucleotide binding site</scene> includes three invariant aspartic acids (D251,D343,and D344), Mg2+ ligand, and hydrophobic tyrosine and valine (Y256 and V342). | The <scene name='60/602706/Active_site_interactions/3'>nucleotide binding site</scene> includes three invariant aspartic acids (D251,D343,and D344)(in blue), Mg2+ ligand, and hydrophobic tyrosine and valine (Y256 and V342)(in green). The aspartic acids aid in catalysis by interacting with the nucleotide bases. Replacing these residues with alanine results in a complete loss in TERT activity, which indicates that they are extremely important in the reverse transcription reaction. The magnesium ligand stabilizes the newly forming DNA strand by interacting with the negatively charges phosphate backbone. Lastly, the hydrophobic residues are hypothesized to structually hold the binding site together hydrophobically and possibly accommodating the base of the nucleotide substrate. | ||
The reverse transcription process begins by the telomerase RNA binding to the 3' end of the overhanging DNA sequence. Once primed, the G-rich sequence (~6-8 nucleotides) polymerizes the end of the DNA. The RNA primer then translocates down the new DNA sequence and polymerizes again. This process repeats until the entire telomere is formed. After one side of the telomere is formed, the telomerase attaches the complementary nucleotide bases to complete the double-stranded telomere at the end of the DNA double helix. | |||
== References == | == References == | ||
<references/> | <references/> | ||
