Function
This gene encodes a protein related to the first discovered blood group system, ABO. Which allele is present in an individual determines the blood group. The 'O' blood group is caused by a deletion of guanine-258 in the gene which corresponds to a region near the N-terminus of the protein. This results in a frameshift and translation of an almost entirely different protein. This mutation results in a protein unable to modify oligosaccharides which end in fucose linked to galactose. This sugar combination is termed the H antigen.
The A and B alleles of the ABO gene express enzymes with glycosyltransferase activities that differ, adding either N-acetyl galactosamine or galactose to the H antigen, converting it into the A or B antigen respectively. Individuals who are heterozygous for this gene express both proteins and so make both A and B antigens. Their blood group is AB. Remarkably, the difference between the A and B glycosyltransferase enzymes is only four amino acids. Other minor alleles have been found for this gene.
Read more about this topic: ABO (gene)
Famous quotes containing the word function:
“The fact remains that the human being in early childhood learns to consider one or the other aspect of bodily function as evil, shameful, or unsafe. There is not a culture which does not use a combination of these devils to develop, by way of counterpoint, its own style of faith, pride, certainty, and initiative.”
—Erik H. Erikson (1904–1994)
“My function in life is not to be a politician in Parliament: it is to get something done.”
—Bernadette Devlin (b. 1947)
“The mother’s and father’s attitudes toward the child correspond to the child’s own needs.... Mother has the function of making him secure in life, father has the function of teaching him, guiding him to cope with those problems with which the particular society the child has been born into confronts him.”
—Erich Fromm (1900–1980)