FKBP12 binding modulates ryanodine receptor channel gating.
The ryanodine receptor (RyR1)/calcium release channel on the sarcoplasmic reticulum of skeletal muscle is comprised of four 565,000-dalton RyR1s, each of which binds one FK506 binding protein (FKBP12). RyR1 is required for excitation-contraction coupling in skeletal muscle. FKBP12, a cis-trans peptidyl-prolyl isomerase, is required for the normal gating of the RyR1 channel. In the absence of FKBP12, RyR1 channels exhibit increased gating frequency, suggesting that FKBP12 "stabilizes" the channel in the open and closed states. We now show that substitution of a Gly, Glu, or Ile for Val2461 in RyR1 prevents FKBP12 binding to RyR1, resulting in channels with increased gating frequency. In the case of the V2461I mutant RyR1, normal channel function can be restored by adding FKBP12.6, an isoform of FKBP12. These data identify Val2461 as a critical residue required for FKBP12 binding to RyR1 and demonstrate the functional role for FKBP12 in the RyR1 channel complex.
Gaburjakova
M
M
Center for Molecular Cardiology and Department of Medicine, Columbia University College of Physicians and Surgeons, New York, New York 10032, USA.
Gaburjakova
J
J
Reiken
S
S
Huang
F
F
Marx
S O
SO
Rosemblit
N
N
Marks
A R
AR
D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001665:Binding Sites; D002110:Caffeine / Q000494:pharmacology; D002460:Cell Line; D006801:Humans; D015640:Ion Channel Gating / Q000502:physiology*; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008861:Microsomes / Q000378:metabolism; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000502:physiology*; D016254:Mutagenesis, Insertional; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000737:chemistry / Q000235:genetics / Q000502:physiology*; D012519:Sarcoplasmic Reticulum / Q000502:physiology*; D022061:Tacrolimus Binding Protein 1A / Q000378:metabolism*; D014162:Transfection; D014633:Valine
D011994:Recombinant Proteins; D019837:Ryanodine Receptor Calcium Release Channel; D002110:Caffeine; D022061:Tacrolimus Binding Protein 1A; D014633:Valine