Alpha Keratin
Alpha keratin is one of the proteins in hair, wool, nails, hoofs and horns. It is also a member of a large family of intracellular keratins found in the cytoskeleton. In keratin fibers, long stretches of alpha helix are interspersed with globular (more compactly folded) regions. This pattern is what gives natural wool fibers their stretchiness. In the keratin represented here, the first 178 amino acids and the last 155 form globular domains on either end of a 310 amino acid fibrous domain. The fibrous region itself is composed of three helical regions separated by shorter linkers. In the fibrous domain, a repeating 7-unit sequence stabilizes the interaction between pairs of helices in two adjacent strands that wind around each other to form a duplex. In the formation of this coil, the more hydrophobic amino acids of the 7-unit sequence meet to form an insoluble core, while charged amino acids on opposing strands attract each other to stabilize the complex.
Alpha Keratin
[ ] = head and tail
( ) = helical segments
{ } = linkers[SRQFSSRSGYRSGGGFSSGSAGIINYQRRTTSSSTRRS
GGGGGRFSSCGGGGGSFGAGGGFGSRSLVNLGGSKSISIS
VARGGGRGSGFGGGYGGGGFGGGGFGGGGFGGGGIGGGG
FGGFGSGGGGFGGGGFGGGGYGGGYGPVCPPGG
IQEVTINQSLLQPLNVEIDPEIQKVKSR]
(EREQIKSLNNQFASFIDKVRFLEQQNQVLQTKWELL)
{QQVDTSTRTHNLEPYFESF}
(INNLRRRVDQLKSDQSRLDSELKNMQDMVEDYRNK
YEDEINKRTNAENEFVTIKKDVDGAYMTKVDLQAK
LDNLQQEIDFLTALYQAELSQM)
{QTQISETNVILSMDNNRSLDLDSI}
(IAEVKAQNEDIAQKSKAEAESLYQSKYEELQITAG
RHGDSVRNSKIEISELNRVIQRLRSEIDNVKKQIS
NLQQSISDAEQRGENALKDAKNKLNDLEDALQQAK
EDLARLLRDYQELMNTKLALDLEIATYRTLLEGE)
[ESRMSGECAPNVSVSVSTSHTTISGGGSRGGGGGGYGSGG
SSYGSGGGSYGSGGGGGGGRGSYGSGGSSYGSGGGSYGSGG
GGGGHGSYGSGSSSGGYRGGSGGGGGGSSGGRGSGGGSSGG
SIGGRGSSSGGVKSSGGSSSVRFVSTTYSGVTR]
Notes on the Music:
The tiny chimes heard throughout the piece are three sets of bells playing through the entire sequence very fast, using different scales. The head section of the protein then fades in, played very slowly. A brisk string section then enters, playing through the sequence again from the beginning, emphasizing the multiple runs of glycines in the head section. Then a reed voice enters, representing the three helical sections of the fibrous region of the protein. The tail section is played by plucked strings, and the reiterated glycines of the tail section are emphasized.