Selective ubiquitination of calmodulin by UBC4 and a putative ubiquitin protein ligase (E3) from Saccharomyces cerevisiae.
A putative ubiquitin protein ligase (E3-CaM) which cooperates with UBC4 in selectively ubiquitinating calmodulin has been partially purified from Saccharomyces cerevisiae. Ca2+ was required for this activity and monoubiquitinated calmodulin was the main product of the reaction. The apparent Km of E3-CaM for calmodulin was approximately 1 microM which is of the same order of magnitude as the concentration of calmodulin in yeast cells. Proteins which are good substrates for other E3s (E3 alpha or E3-R) were not ubiquitinated by E3-CaM. Lower but significant activities of E3-CaM were observed when UBC1 replaced UBC4.
Department of Biological Chemistry, Alexander Silberman Institute of Life Sciences, Hebrew University of Jerusalem, Israel.
H A
HA
Parag
D
D
Dimitrovsky
B
B
Raboy
R G
RG
Kulka
D002147:Calmodulin / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D008025:Ligases / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013379:Substrate Specificity; D044763:Ubiquitin-Conjugating Enzymes; D044767:Ubiquitin-Protein Ligases; D014452:Ubiquitins / Q000378:metabolism*
D002147:Calmodulin; D014452:Ubiquitins; D044763:Ubiquitin-Conjugating Enzymes; C063109:ubiquitin-conjugating enzyme UBC4; D044767:Ubiquitin-Protein Ligases; D008025:Ligases