ubiquitination is one method used by cells to regulate protein levels. why do you think cells sometimes use this method of regulating protein levels rather than regulating the level of gene transcription/translation? what would happen in a cell with a mutated apc/c that fails to ubiquitylate germinin? explain your answer. what would happen in a cell with a mutated mdm2 protein that fails to ubiquitylate p53? explain your answer.
