The function of hemoglobin in oxygen transport by red blood cells requires precise assembly of a tetramer of two beta-subunits and two alpha-units. If too many beta-subunits are present, then all tetramers of beta-subunits are formed that bind oxygen but do not release it when needed. When alpha-subunits are in excess they form precipitates with oxidized heme that damage red blood cells. Red blood cells require a precise coregulation of alpha and beta subunit expression to maintain the proper ratio of the subunits and normal red blood cell function. Generally red blood cells express slightly more alpha than beta-subunits to avoid forming unproductive beta-tetramers (HbH). The slight excess of alpha units are blocked from precipitation by a molecular chaperone, AHSP, alpha-hemoglobin stabilizing protein. Expression of the AHSP gene is coordinately activated with the globin genes and heme biosynthesis genes by the GATA-1 gene involved in erythrocyte differentiation. AHSP blocks precipitation of alpha-units, and promotes the formation of normal productive alpha-beta tetramers (HbA). People with mutation or deletion of the beta-subunit gene have Beta-thalassemias resulting from an over-abundance of alpha subunits and their precipitation. The severity of the phenotype may depend on the AHSP genotype of these individuals and elevating AHSP levels through gene therapy may provide a treatment strategy for beta-thalassemia.
7.0: Changed members. Upgraded to final version of Biocarta.
License Terms for BioCarta data in MSigDB
MSigDB gene sets derived from BioCarta pathways are protected by copyright, (c) 2000-2017 BioCarta, all rights reserved. They are provided
under license to the Broad Institute, Inc. with qualified permission to include in this release, subject to Biocarta's
"Disclaimer
of Liability and of Warranties" (formerly found at www.biocarta.com). Inclusion of these gene
sets is conditioned upon acknowledgment and retention of the aforementioned copyright, and agreement to such disclaimer. The BioCarta
derived gene sets are in the MSigDB C2 and M2 collections, and can be recognized by the "BIOCARTA_" prefix in their name.
