pol(a) polymerases showed various genetic interactions with dna topoisomerases top1p and hence they were called topoisomerase-related function trf4p and trf5p due to this interaction with dna it has an important part in genomic stability. in the cell trf4p is in higher concentration as compared to trf5p and also has a stronger effect on the phenotype. trf4p is present throughout the nucleus while trf5p is mainly found mainly in nucleolus. the trf4p structure consists of a central domain and a catalytic domain which is similar to the structure of canonical polymerases.