Association of initiation factor eIF-2 with a rapidly sedimenting fraction from Ehrlich ascites-tumour cells

To determine the subcellular distribution of initiation-factor eIF-2 activity, Ehrlich ascites-cell homogenates were fractionated to give (a) a rapidly sedimenting fraction, (b) a microsomal fraction and (c) post-microsomal supernatant. The first two fractions were washed in 0.5 m-KCl to render the associated protein-synthesis factor soluble. As much as 60% of the total recoverable eIF-2 was obtained from the rapidly sedimenting material.