1H and 15N assignment of NMR spectrum, secondary structure and global folding of the immunophilin-like domain of the 59-kDa FK506-binding protein.

FKBP59, a 59-kDa FK506 binding protein, was discovered in heterooligomeric complexes containing nontransformed, non-DNA binding, steroid receptors. Sequence similarity search and secondary structure prediction suggested that the protein has a multi-domain organization, the N-terminal domain having a great similarity to human FKBP12 (12-kDa FK506-binding protein). FKBP59 binds immunosuppressant FK506 and has peptidylprolyl cis-trans-isomerase activity, both properties being localized in the N-terminal domain (FKBP59-I).

Rabbit FKBP-59/HBI does not inhibit calcineurin activity in vitro.

The effect of recombinant FKBP-59/HBI or of its first N-terminal domain FKBP-59/HBI-I on the phosphatase activity of calcineurin (a Ca(+2)-calmodulin dependent phosphatase) was tested in vitro in the presence or absence of the immunosuppressant drug FK506. Contrarily to the inhibition observed with the immunosuppressant complex FKBP-12-FK506, no significant inhibition was observed with FKBP-59/HBI or FKBP-59/HBI-I in the presence of FK506, even though FKBP-59/HBI-1 is nearly 55% homologous to the immunophilin FKBP-12. Inhibition was tested both with native calcineurin (calcineurin A: Mr 58-59 kDa) and with protease activated, calmodulin independent calcineurin (calcineurin A: Mr 45 kDa).

Role of tyrosine 143 in lactate dehydrogenation by flavocytochrome b2. Primary kinetic isotope effect studies with a phenylalanine mutant.

Flavocytochrome b2 catalyzes the oxidation of lactate at the expense of cytochrome c. After flavin (FMN) reduction by the substrate, reducing equivalents are transferred one by one to heme b2, and from there on to cytochrome c. The crystal structure of the enzyme is known at 2.

Overexpression of p59-HBI (FKBP59), full length and domains, and characterization of PPlase activity.

It has been previously proposed that the rabbit p59-HBI (Heat shock protein Binding Immunophilin) or rFKBP59 (FK506 Binding Protein), found associated with the 90 kDa heat shock protein in nontransformed steroid receptor complexes, has three domains structurally related to hFKBP12 (Callebaut, I., Renoir, J.M.