Human globin psi B2 is not a globin-related sequence.

We have determined the complete nucleotide sequence of 3.4 kilobase pairs of DNA covering the region of the human beta globin gene cluster where a human globin-related sequence psi beta 2 was thought to lie (Fritsch, Lawn, and Maniatis (1980) Cell 19, 959-972). Analysis of the resulting data reveals no evidence for any globin-related sequences in this region. The region does, however, contain several stretches of poly (dA-dT). We have confirmed the observations of Fritsch et al. that DNA from the psi beta 2 region hybridizes to the poly (dA-dT)-tailed human fetal globin cDNA plasmid, pJW151 (Wilson et al., (1978) Nucl. Acids Res. 5, 563-581) under conditions of low stringency, but we find that this hybridization is abolished by the addition of poly(rA). We conclude that psi beta 2 is not a globin pseudogene, and that the earlier investigators were probably misled by hybridization between the poly (dA-dT) stretches within the psi beta 2 region and the tails used in constructing the cDNA plasmid.