serpin

noun

ser·pin ˈsir-pən

ˈser-

: any of a group of structurally related proteins (as antithrombin and antitrypsin) that are typically inhibitors of proteases having serine as the main functional group and that include some (as ovalbumin and angiotensinogen) which have lost their inhibitory action

The identification of an intracellular serpin (protease inhibitor) that prevents necrosis caused by multiple noxious stimuli indicates that necrosis can be regulated, programmed, and driven by a peptidase stress-response pathway.—

Richard S. Hotchkiss et al., The New England Journal of Medicine

Apparently evolution has completely adapted the serpin structure for its new role in these proteins as a transport agent, as there is no evidence of any retained protease inhibitory activity.—

Daniel F. Voytas et al., letter in Nature