Atomic force microscopy used in in vitro studies have shown that circular eukaryotic polysomes can be formed by free polyadenylated mRNA in the presence of initiation factor eIF4E bound to the 5’ cap and PABP bound to the 3’-poly(A) tail. However, this interaction between cap and poly(A)-tail mediated by a protein complex is not a unique way of circularizing polysomal mRNA. It has been found that topologically circular polyribosomes can be successfully formed in the translational system with mRNA with no cap and no poly(A) tail as well as a capped mRNA without a 3’-poly(A) tail.[1]