Targets of immunophilin-immunosuppressant complexes are distinct highly conserved regions of calcineurin A.
Journal Article (Journal Article)
The immunosuppressive complexes cyclophilin A-cyclosporin A (CsA) and FKBP12-FK506 inhibit calcineurin, a heterodimeric Ca(2+)-calmodulin-dependent protein phosphatase that regulates signal transduction. We have characterized CsA- or FK506-resistant mutants isolated from a CsA-FK506-sensitive Saccharomyces cerevisiae strain. Three mutations that confer dominant CsA resistance are single amino acid substitutions (T350K, T350R, Y377F) in the calcineurin A catalytic subunit CMP1. One mutation that confers dominant FK506 resistance alters a single residue (W430C) in the calcineurin A catalytic subunit CMP2. In vitro and in vivo, the CsA-resistant calcineurin mutants bind FKBP12-FK506 but have reduced affinity for cyclophilin A-CsA. When introduced into the CMP1 subunit, the FK506 resistance mutation (W388C) blocks binding by FKBP12-FK506, but not by cyclophilin A-CsA. Co-expression of CsA-resistant and FK506-resistant calcineurin A subunits confers resistance to CsA and to FK506 but not to CsA plus FK506. Double mutant calcineurin A subunits (Y377F, W388C CMP1 and Y419F, W430C CMP2) confer resistance to CsA, to FK506 and to CsA plus FK506. These studies identify cyclophilin A-CsA and FKBP12-FK506 binding targets as distinct, highly conserved regions of calcineurin A that overlap the binding domain for the calcineurin B regulatory subunit.
Full Text
Duke Authors
Cited Authors
- Cardenas, ME; Muir, RS; Breuder, T; Heitman, J
Published Date
- June 15, 1995
Published In
Volume / Issue
- 14 / 12
Start / End Page
- 2772 - 2783
PubMed ID
- 7540976
Pubmed Central ID
- PMC398395
International Standard Serial Number (ISSN)
- 0261-4189
Digital Object Identifier (DOI)
- 10.1002/j.1460-2075.1995.tb07277.x
Language
- eng
Conference Location
- England