OCA2: Oculocutaneous Albinism
Oculocutaneous albinism is a condition in which pigment is greatly reduced in the retina and in the skin and hair. Defects in OCA2 are responsible for the most common form of albinism in humans. It may also be involved in the determination of blue and brown eye color. The gene OCA2 is located on human chromosome 15 at position q11-12. The gene is biggish, spanning over 340,000 nucleotides and is divided into 24 exons. The sequence of the encoded protein, which contains 838 amino acids, is given below. The protein is a membrane transporter with 12 transmembrane domains. It probably transports tyrosine or other precursors of the pigment melanin in pigment cells. Similar proteins are found in other animals, and albinism in mice and in cavefish has also been attributed to defects in OCA2.
OCA2
Human Sequence( ) = Cytoplasmic Domain
[ ] = Transmembrane Domain
{ } = Extracellular Domain
M(HLEGRDGRRYPGAPAVELLQTSVPSGLAELVAGKRRLPRGAGG
ADPSHSCPRGAAGQSSWAPAGQEFASFLTKGRSHSSLPQMSSSRS
KDSCFTENTPLLRNSLQEKGSRCIPVYHPEFITAEESWEDSSADW
ERRYLLSREVSGLSASASSEKGDLLDSPHIRRLSKLRRCVQWLK)[VMGLFAFVVLCSILFSLY]
{PDQGKLWQLLALSPLENYSVNLSSHVDSTLLQVDLAGALVASGP
SRPGREEHIVVELTQDDALGSRWRRPQQVTHNWTVYLNPRRSEHS
VMSRTFEVLTRETVSISIRASLQQTQAVPLLMAHQYLRGSVETQ}
[VTIATAILAGVYALIIF](EIVHRT)
[LAAMLGSLAALAALAVI]
{GDRPSLTHVVEWID}
[FETLALLFGMMILVAIF](SETGFFDYCAVKAYRLSRGRVW)
[AMIIMLCLIAAVLSAFL]
{DNVTTMLLFTPVTIRLCEVLNLDPRQVLIAEVIFTNI
GGAATAIGDPPNVIIVSNQELRKMGLDFAGFTAHMF}
[IGICLVLLVCFPLLRLL](YWNRKLYNKEPSEIVELKHEIHVWRLTAQR
ISPASREETAVRRLLLGKVLALEHLLARRLH
TFHRQISQEDKNWETNIQELQKKHRISDG)
[ILLAKCLTVLGFVIFMF]
{FLNSFVPGIH}
[LDLGWIAILGAIWLLIL](ADIHDFEIILHRVEW)
[ATLLFFAALFVLMEALA]
{HLHLIEYVGEQTALLIKMVPEEQR}
[LIAAIVLVVWVSALASS](LIDNIPFTATMIPVLLNLSHDPE)
[VGLPAPPLMYALAFGAC]
{LGGNGTLIGASANVVCAGIAEQHGYGFSFMEFFRLGFPMM}
[VVSCTVGMCYLLVAHVV]
VGWN~
Notes on the Music:
This piece is a single read-through of the OCA2 protein sequence. The piece begins with the long cytoplasmic domain represented by harp and chimes, the harp playing the more soluble amino acids usually found near the surface of proteins and the chimes playing the less soluble amino acids usually located in the interior. The entrance of a a string section identifies the first of the six transmembrane loops, in which the protein crosses the cell membrane and then returns to the interior of the cell. Each of these is set off in a separate paragraph in the sequence above. The strings will play through the two transmembrane domains of each loop. After the completion of the first loop, the chimes representing the less soluble amino acids are replaced by a flute for the short second loop, and are followed by solo piano for the third loop. The flute returns for the fourth loop, and then the chimes play through the fifth and sixth to the end of the piece.
This piece was composed using MusicWonk sequencing software from Algorithmic Arts.
More information on OCA2: