Hemoglobin subunit gamma-2 is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
that in humans is encoded by the ''HBG2''
gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
.
Function
The gamma globin genes (
HBG1
Hemoglobin subunit gamma-1 is a protein that in humans is encoded by the ''HBG1'' gene.
Function
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 c ...
and HBG2, this gene) 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-thalassemia
Beta-thalassemia (β-thalassemia) is an inherited blood disorder, a form of thalassemia resulting in variable outcomes ranging from clinically asymptomatic to severe anemia individuals. It is caused by reduced or absent synthesis of the beta ...
s and related conditions, gamma chain production continues into adulthood. The two types of gamma chains differ at residue 136 where
glycine
Glycine (symbol Gly or G; ) is an amino acid that has a single hydrogen atom as its side chain. It is the simplest stable amino acid. Glycine is one of the proteinogenic amino acids. It is encoded by all the codons starting with GG (G ...
is found in the G-gamma product (HBG2) and
alanine
Alanine (symbol Ala or A), or α-alanine, is an α-amino acid that is used in the biosynthesis of proteins. It contains an amine group and a carboxylic acid group, both attached to the central carbon atom which also carries a methyl group sid ...
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
Epsilon (, ; uppercase , lowercase or ; ) is the fifth letter of the Greek alphabet, corresponding phonetically to a mid front unrounded vowel or . In the system of Greek numerals it also has the value five. It was derived from the Phoenic ...
– gamma-G –
gamma-A –
delta
Delta commonly refers to:
* Delta (letter) (Δ or δ), the fourth letter of the Greek alphabet
* D (NATO phonetic alphabet: "Delta"), the fourth letter in the Latin alphabet
* River delta, at a river mouth
* Delta Air Lines, a major US carrier ...
–
beta
Beta (, ; uppercase , lowercase , or cursive ; or ) is the second letter of the Greek alphabet. In the system of Greek numerals, it has a value of 2. In Ancient Greek, beta represented the voiced bilabial plosive . In Modern Greek, it represe ...
- 3'.
References
Further reading
*
*
External links
*
Hemoglobins
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