GYPA
Description
The GYPA (glycophorin A (MNS blood group)) is a protein-coding gene located on chromosome 4.
Glycophorin A (MNS blood group), also known as GYPA, is a protein which in humans is encoded by the GYPA gene. GYPA has also recently been designated CD235a (cluster of differentiation 235a).
Glycophorins A (GYPA; this protein) and B (GYPB) are major sialoglycoproteins of the human erythrocyte membrane which bear the antigenic determinants for the MN and Ss blood groups. In addition to the M or N and S or s antigens, that commonly occur in all populations, about 40 related variant phenotypes have been identified. These variants include all the variants of the Miltenberger complex and several isoforms of Sta; also, Dantu, Sat, He, Mg, and deletion variants Ena, S-s-U- and Mk. Most of the variants are the result of gene recombinations between GYPA and GYPB.
GypA, GypB and GypE are members of the same family and are located on the long arm of chromosome 4 (chromosome 4q31). The family evolved via two separate gene duplication events. The initial duplication gave rise to two genes one of subsequently evolved into GypA and the other which give rise via a second duplication event to GypB and GypE. These events appear to have occurred within a relatively short time span. The second duplication appears to have occurred via an unequal crossing over event. The GypA gene itself consists of 7 exons and has 97% sequence homology with GypB and GypE from the 5' untranslated transcription region (UTR) to the coding sequence encoding the first 45 amino acids.
Glycophorin A (GYPA) is a crucial component of the ankyrin-1 complex, a multiprotein assembly that plays a vital role in maintaining the stability and shape of the erythrocyte membrane. As the major intrinsic membrane protein of the erythrocyte, GYPA possesses MN blood group receptors on its N-terminal glycosylated segment, which protrudes from the erythrocyte membrane. GYPA appears to be essential for the proper function of SLC4A1, a protein responsible for transporting bicarbonate across the red blood cell membrane. GYPA is required for high SLC4A1 activity and may even be involved in its translocation to the plasma membrane.
GYPA is also known as CD235a, GPA, GPErik, GPSAT, HGpMiV, HGpMiXI, HGpSta(C), MN, MNS, PAS-2.
