Description
Description: This assay employs a two-site sandwich ELISA to quantitate HBG1 in samples. An antibody specific for HBG1 has been pre-coated onto a microplate. Standards and samples are pipetted into the wells and any HBG1 present is bound by the immobilized antibody. After removing any unbound substances, a biotin-conjugated antibody specific for HBG1 is added to the wells. After washing, Streptavidin conjugated Horseradish Peroxidase (HRP) is added to the wells. Following a wash to remove any unbound avidin-enzyme reagent, a substrate solution is added to the wells and color develops in proportion to the amount of HBG1 bound in the initial step. The color development is stopped and the intensity of the color is measured.
Overview: The gamma globin genes (HBG1 and HBG2) are normally expressed in the fetal liver, spleen and bone marrow. Two gamma chains together with two alpha chains constitute fetal hemoglobin (HbF) which is normally replaced by adult hemoglobin (HbA) at birth. In some beta-thalassemias and related conditions, gamma chain production continues into adulthood.
The two types of gamma chains differ at residue 136 where glycine is found in the G-gamma product (HBG2) and alanine is found in the A-gamma product (HBG1). The former is predominant at birth. The order of the genes in the beta-globin cluster is: 5'-epsilon -- gamma-G -- gamma-A -- delta -- beta--3'