Characterization of reticulocyte release factor.

The release factor (RF) of reticulocytes has been purified to greater than 75% homogeneity. The RF has a native molecular weight of 105,000 and subunit molecular weight of 56,500. The RF protein will bind to reticulocyte ribosomes in response to UAAA, UAGA, or UGAA and therefore participates in codon recognition. The fraction possess a ribosome-dependent GTPase activity. The RF is stimulated in its activity by a second protein fraction.