INVESTIGADORES
ROSSI Silvia Graciela
artículos
Título:
novel activating effect of the regulatory subunit of protein kinase a on catalytic subunit activity
Autor/es:
- RINALDI J, OCAMPO J, ROSSI S AND MORENO S
Revista:
ARCHIVES OF BIOCHEMISTRY AND BIOPHYSICS
Editorial:
ELSEVIER SCIENCE INC
Referencias:
Año: 2008 vol. 480 p. 95 - 103
ISSN:
0003-9861
Resumen:
The strength of the interaction
between the catalytic
and regulatory
subunits
in protein
kinase A differs
among species.
The linker region from regulatory
subunits
is non-conserved.
To evaluate
the participation
of this region in the interaction
with the catalytic
subunit,
we have assayed its effect on the enzymatic
properties
of the catalytic
subunit.
Protein
kinase A from three fungi, Mucor rouxii,Mucor rouxii,
Mucor circinelloides
and Saccharomyces
cerevisiaeSaccharomyces
cerevisiae
have been chosen
as models.
The RC interaction
is explored by using synthetic
peptides
of 8, 18 and 47 amino acids, corresponding
to the R subunit
autophosphorylation
site plus
a variable
region toward the N terminus
(0, 10, or 39 residues).
The Km of the catalytic
subunits
decreased
with the length of the peptide,
while the Vmax increased. Viscosity
studies
identified
product
release as
the rate limiting
step for phosphorylation
of the longer peptides.
Pseudosubstrate
derivatives
of the 18
residue
peptides
did not display
a competitive
inhibition
behavior
toward either kemptide
or a bona fideKm of the catalytic
subunits
decreased
with the length of the peptide,
while the Vmax increased. Viscosity
studies
identified
product
release as
the rate limiting
step for phosphorylation
of the longer peptides.
Pseudosubstrate
derivatives
of the 18
residue
peptides
did not display
a competitive
inhibition
behavior
toward either kemptide
or a bona fideVmax increased. Viscosity
studies
identified
product
release as
the rate limiting
step for phosphorylation
of the longer peptides.
Pseudosubstrate
derivatives
of the 18
residue
peptides
did not display
a competitive
inhibition
behavior
toward either kemptide
or a bona fidebona fide
protein
substrate
since, at low relative
pseudosubstrate/
substrate
concentration,
stimulation
of kemptide
or protein
substrate
phosphorylation
was observed. The behavior
was mimicked
by intact R. We conclude
that in addition
to its negative
regulatory
role, the R subunit
stimulates
C activity
via distal
interactions.