A toxin-like gene in rainbow trout: cloning, expression, and gene organization.

The 'three-finger' protein family consists of structurally related proteins which display a variety of biological functions. Snake venom alpha-neurotoxins, Ly-6 alloantigens, urokinase-type plasminogen activator receptor (uPAR) and the complement regulatory protein CD59 are members of this protein family. Their characteristic feature is the disposition of four disulfide bridges forming a hydrophobic core.

Cloning of a CD59-like gene in rainbow trout. Expression and phylogenetic analysis of two isoforms.

CD59, the major inhibitor of the complement membrane attack complex, is an 18-20 kDa glycoprotein, linked to the membrane via a glycosylphosphatidylinositol (GPI)-anchor. It restricts binding of C9 to the C5b-8 complex, preventing the formation of the complement membrane attack complex C5b-9. In this study we report the cloning of a second CD59-like gene in the rainbow trout, Oncorhynchus mykiss (referred to as CD59-2 and the previously deposited trout CD59-like gene as CD59-1).