... meager. In the head -to- tail orientation, the catalytic site in the N-terminal domain of one subunit and the substrate recognition site in the C-terminal domain of the other face each other, thereby ... procolipase. The PL cofactor, procolipase, binds to the C-terminaldomain of PL and interacts with the surface loop, presum-ably stabilizing the open form [18,19]. LPL requires the cofactor apoC-II ... Lys428, and Lys430) oriented in the same direction with the heparin-binding domain at the N-terminal end [14]. The other is a cluster of tryptophans(Trp390, Trp393, and Trp394) exposed to the surface(Fig....