During which part of the cell cycle are SCF complexes active

During which part of the cell cycle are SCF complexes active? from mitosis through the beginning of G_1 from S phase through the end of G_2 only during S phase from late G_1 through early mitosis

Solution

Skp, Cullin, F-box containing complex (or SCF complex) is an E3 ubiquitin ligase which catalyses the degradation of proteins via proteasomal degradation.

During G1/S phase it ubiquitinylated and degrade p27 and p21 so that cell can proceed towards S phase

During G2/M phaseSCF complex degrade Wee1 protein.

During M-phase it ubiquitinylated securin which holds both the chromatids together.

Answer will be option D from late G1 through early mitosis