title: The ninth component of complement and the pore-forming protein (perforin 1) from cytotoxic T cells: structural, immunological, and functional similarities.
abstract: The ninth component of complement (C9) and the pore-forming protein (PFP or perforin) from cytotoxic T lymphocytes polymerize to tubular lesions having an internal diameter of 100 A and 160 A, respectively, when bound to lipid bilayers. Polymerized C9, assembled by slow spontaneous or rapid Zn2+-induced polymerization, and polyperforin, which is assembled only in the presence of Ca2+, constitute large aqueous pores that are stable, nonselective for solutes, and insensitive to changes of membrane potential. Monospecific polyclonal antibodies to purified C9 and PFP show cross-reactivity, suggesting structural homology between the two molecules. The structural and functional homologies between these two killer molecules imply an active role for pore formation during cell lysis.
mesh_terms: D000818:Animals; D002500:Centrifugation, Isopycnic; D003186:Complement C9 / Q000276:immunology* / Q000502:physiology; D003429:Cross Reactions; D006801:Humans; D007473:Ion Channels / Q000502:physiology; D008562:Membrane Glycoproteins; D008565:Membrane Proteins / Q000276:immunology* / Q000502:physiology; D051379:Mice; D008970:Molecular Weight; D054353:Perforin; D052899:Pore Forming Cytotoxic Proteins; D013602:T-Lymphocytes, Cytotoxic / Q000502:physiology*; D015032:Zinc / Q000502:physiology
chemical_list: D003186:Complement C9; D007473:Ion Channels; D008562:Membrane Glycoproteins; D008565:Membrane Proteins; D052899:Pore Forming Cytotoxic Proteins; D054353:Perforin; D015032:Zinc