Lysine residues 165 and 166 are essential for the cofactor function of tissue factor.
Tissue factor, a 45-kilodalton membrane glycoprotein, is an essential cofactor for the plasma serine protease factor VII which activates factor X in the first step of the extrinsic coagulation cascade. Two adjacent lysine residues (numbers 165 and 166) were identified in the extracytoplasmic domain of tissue factor that are crucial for function. Site-directed mutagenesis of both lysines to alanines results in complete loss of activity. Mutation of either lysine alone results in a molecule which is much more sensitive to the phospholipid composition of the activating surface than the wild-type molecule. It is postulated that interactions between the extracytoplasmic domain of tissue factor and the membrane surface are necessary for bound factor VII or VIIa to assume a conformation capable of efficient catalysis.
Roy
S
S
Genetech Inc., South San Francisco, California 94080.
Hass
P E
PE
Bourell
J H
JH
Henzel
W J
WJ
Vehar
G A
GA
D000595:Amino Acid Sequence; D001483:Base Sequence; D002460:Cell Line; D005167:Factor VII / Q000378:metabolism*; D005822:Genetic Vectors; D006801:Humans; D007700:Kinetics; D008239:Lysine; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides; D010449:Peptide Mapping; D010743:Phospholipids / Q000494:pharmacology; D013925:Thromboplastin / Q000235:genetics* / Q000378:metabolism*; D014162:Transfection
D009838:Oligodeoxyribonucleotides; D010743:Phospholipids; D005167:Factor VII; D013925:Thromboplastin; D008239:Lysine