Stable globin needs a partner

In the absence of a binding partner, such as when β-globin is mutated in β-thalassemia, the unstable α-globin protein tends to form toxic inclusion bodies. Molecular chaperones that stabilize hemoglobin have been proposed to exist, but have not been found, until now. Anthony Kihm, Mitchell Weiss, and colleagues (University of Pennsylvania, Philadelphia, PA) have now identified a protein that protects α-globin until it can find β-globin and form hemoglobin A (HbA).

This chaperone-like protein, AHSP, was identified in a screen for genes induced by the transcription factor GATA-1, which promotes erythrocyte differentiation. Many genes were induced by GATA-1, but Weiss found AHSP particularly interesting because it was strongly and specifically expressed in RBCs and had no known function. Screens for protein–protein interactions revealed that AHSP bound to α-globin, but not to β-globin or HbA.

AHSP prevented α-globin...