DNA binding proteins from calf thymus with an enhanced ability to stimulate DNA polymerase α in vitro

We have isolated from calf thymus glands a new class of single-stranded DNA binding proteins (DBP) specifically endowed with the ability to stimulate DNA polymerase α activity $\text{in vitro}$. Such result was attained by using a partially new purification procedure and a functional assay, i.e. stimulation of DNA polymerase α on poly(dAT) throughout purification. We observed stimulations up to 30-fold of DNA polymerase α on poly(dAT) at a protein: DNA ratio of 1:1, that is much below the saturating level. Such stimulation is specific for DNA polymerase α. These results indicate a possible direct functional interaction between our DBP, polymerase α and the template.