Beta-globin is a component (subunit) of a larger protein called hemoglobin, which is located inside red blood cells. In adults, hemoglobin normally consists of four protein subunits: two subunits of beta-globin and two subunits of a protein called
alpha-globin
, which is produced from another gene called HBA.
What is the function of beta globin?
The beta globin protein is one of the subunits of hemoglobin, a protein necessary for
the oxygen-carrying function of red blood cells
. People with the sickle cell mutation in both copies of the HBB gene produce proteins that clump together and lead to changes in the shape and behavior of red blood cells.
What is the difference between alpha and beta globin?
Key Points. The normal hemoglobin (Hb A) in adults contains two α chains and two β chains. Each α chain contains 141 amino acids, and each β chain contains 146 amino acids. Hb A
2
contains two α chains and two δ chains.
What does HBB mean in biology?
HBB (
Hemoglobin Subunit Beta
) is a Protein Coding gene. Diseases associated with HBB include Beta-Thalassemia and Sickle Cell Anemia.
What is the DNA sequence of hemoglobin?
The specific base sequence for these amino acids is:
GTG/CAC/CTG/ACT/CCT/GAG
. Sickle cell hemoglobin (Hemoglobin S) results when, glutamic acid that is normally present in the sixth position on the beta globin chain is substituted with valine.
Is beta thalassemia worse than alpha?
Alpha thalassemia major with hemoglobin Bart’s usually results in fatal hydrops fetalis. Beta thalassemia major causes hemolytic anemia, poor growth, and skeletal abnormalities during infancy. Affected children will require regular lifelong blood transfusions.
Can beta thalassemia be cured?
Blood transfusions
and chelation do not cure beta thalassemia
. A stem cell transplant can cure it, but it is a serious procedure with many risks and won’t benefit everyone with the condition. Doctors and scientist are working on developing gene therapies and other treatments to help people with beta thalassemia.
Is beta globin a protein?
Beta-globin is
a component (subunit) of a larger protein called hemoglobin
, which is located inside red blood cells. In adults, hemoglobin normally consists of four protein subunits: two subunits of beta-globin and two subunits of a protein called alpha-globin, which is produced from another gene called HBA.
What is the meaning of globin?
:
a colorless protein obtained by removal of heme from a conjugated protein and especially hemoglobin
.
What causes beta thalassemia?
Beta thalassemia is caused by
mutations in the hemoglobin beta (HBB) gene
. Individuals with beta thalassemia minor have a mutation in one HBB gene, while individuals with the intermediate and major forms have mutations in both HBB genes.
How many alpha globin genes are there?
Alpha Globin Locus
For practical purposes, the two alph globin genes (termed alpha1 and alpha2) are identical. Since each cell has two chromosomes 16, a total of
four alpha globin genes
exist in each cell.
How is the beta globin polypeptide produced?
HbS is produced by
a point mutation in HBB in which the codon GAG is replaced by GTG
. This results in the replacement of hydrophilic amino acid glutamic acid with the hydrophobic amino acid valine at the sixth position (β6Glu→Val).
How big is the beta globin gene?
The β-globin gene cluster occupies a region of
approximately 17 kb
on the short arm of chromosome 11. Each of its constituent genes, their flanking regions, and large stretches of the regions between them have been sequenced.
What is the normal hemoglobin amino acid?
In normal hemoglobin, the amino acid at position seven is
glutamate
. In sickle cell hemoglobin, this glutamate is replaced by a valine. The unique sequence for every protein is ultimately determined by the gene encoding the protein.
How is thalassemia inherited?
Thalassemia major and thalassemia intermedia are inherited in
an autosomal recessive pattern
, which means both copies of the HBB gene in each cell have mutations.
What are hemoglobin mutations?
Abnormal hemoglobins result from mutations that
change the sequence or number of nucleotides within the globin gene involved
, or more rarely, from mispairing and crossover between two like genes during meiosis, creating a fusion protein of both gene sequences.
