The integrity of tubulin molecule is not required for the activity of tubulin carboxypeptidase.
Tubulin dimer, alpha-tubulin subunit, and C-terminal peptides obtained from the alpha-tubulin subunit were compared in their capabilities to act as substrates of tubulin carboxypeptidase. The results obtained indicate that the enzyme does not require the beta-tubulin subunit to release tyrosine from alpha-tubulin. The 17-Kd C-terminal peptide of the alpha-tubulin subunit was obtained and it was detyrosinated at the same rate as tubulin dimer. A smaller C-terminal peptide of 2.8-3.7 Kd showed a lower capability to act as substrate. Similar results were obtained with pancreatic carboxypeptidase A. From the analysis of the results we consider that an optimal activity of the tubulin carboxypeptidase depends mainly on the accessibility of the C-terminal end of alpha-tubulin.
Weizetfel
J C
JC
Centro de Investigaciones en Química Biológica de Córdoba, UNC-CONICET, Argentina.
Argaraña
C E
CE
Beltramo
D M
DM
Barra
H S
HS
D000595:Amino Acid Sequence; D000818:Animals; D002268:Carboxypeptidases / Q000378:metabolism* / Q000502:physiology; D004789:Enzyme Activation; D007700:Kinetics; D010446:Peptide Fragments / Q000302:isolation & purification / Q000502:physiology; D011487:Protein Conformation; D051381:Rats; D013379:Substrate Specificity; D014404:Tubulin / Q000502:physiology*; D014443:Tyrosine / Q000378:metabolism
D010446:Peptide Fragments; D014404:Tubulin; D014443:Tyrosine; D002268:Carboxypeptidases