Inhibition of protein synthesis by the beta-subunit of spectrin

The 220 kDa beta-subunit of erythroid cell spectrin is a potent inhibitor of protein synthesis in lysates from rabbit reticulocytes. On the basis of weight of protein added to a lysate reaction mixture, it has about half the inhibitory activity of highly purified heme-regulated eIF-2 alpha kinase. Inhibition appears to be at the level of peptide initiation but does not involve a kinase that phosphorylates eIF-2 on its alpha-subunit.