Perforin is activated by a proteolytic cleavage during biosynthesis which reveals a phospholipid-binding C2 domain.
EMBO J
; 16(24): 7287-96, 1997 Dec 15.
Article
in En
| MEDLINE
| ID: mdl-9405358
ABSTRACT
Perforin is a secreted protein synthesized by activated cytotoxic T lymphocytes (CTL) and natural killer (NK) cells. It is a key component of the lytic machinery of these cells, being able to insert into the plasma membrane of targeted cells, forming a pore which leads to their destruction. Here we analyse the synthesis, processing and intracellular transport of perforin in the NK cell line YT. Perforin is synthesized as a 70 kDa inactive precursor which is cleaved at the C-terminus to yield a 60 kDa active form. This proteolytic cleavage occurs in an acidic compartment and can be inhibited by incubation of the cells in ammonium chloride, concanamycin A, leupeptin and E-64. The increased lytic activity of the cleaved form can be demonstrated by killing assays in which cleavage of the pro-piece is inhibited. Epitope mapping reveals that cleavage of the pro-piece occurs at the boundary of a C2 domain, which we show is able to bind phospholipid membranes in a calcium-dependent manner. We propose that removal of the pro-piece, which contains a bulky glycan, allows the C2 domain to interact with phospholipid membranes and initiate perforin pore formation.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Phospholipids
/
Protein Conformation
/
Membrane Glycoproteins
/
Killer Cells, Natural
/
T-Lymphocytes, Cytotoxic
/
Protein Processing, Post-Translational
Limits:
Animals
/
Humans
Language:
En
Journal:
EMBO J
Year:
1997
Document type:
Article
Affiliation country:
United kingdom