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Skp2 is the substrate recruiting component of the SCFSkp2 complex, which targets cell cycle control elements, such as p27 and p21. [28] [29] [30] Here, SKP2 has been implicated in double negative feedback loops with both p21 and p27, that control cell cycle entry and G1/S transition. [31] [32]
During S phase, Cdc6 and Cdt1 are degraded or inactivated to block additional pre-RC formation, and bidirectional DNA replication ensues. When the replication fork encounters lesions in the DNA, the S-phase checkpoint response slows or stops fork progression and stabilizes the association of MCM2-7 with the replication fork during DNA repair.
Skp, Cullin, F-box containing complex (or SCF complex) is a multi-protein E3 ubiquitin ligase complex that catalyzes the ubiquitination of proteins destined for 26S proteasomal degradation. [1] Along with the anaphase-promoting complex, [2] SCF has important roles in the ubiquitination of proteins involved in the cell cycle. The SCF complex ...
DnaA is a protein that activates initiation of DNA replication in bacteria. [1] Based on the Replicon Model, a positively active initiator molecule contacts with a particular spot on a circular chromosome called the replicator to start DNA replication. [2]
The RING protein appears to function as a docking site for ubiquitin-conjugating enzymes (E2s). Other proteins contain a cullin-homology domain, such as CUL9 , also known as p53 cytoplasmic anchor PARC , and the ANAPC2 subunit of the anaphase-promoting complex/cyclosome; both CUL9 and ANAPC2 have ubiquitin ligase activity.
Fig. 1 The figure shows a sketch of how the SCF complex functions, and what the role of Cdc4 is within this structure (-> adaptor function). Various cellular regulatory mechanisms heavily depend on ubiquitin-dependent degradation. The SCF (Cdc4) complex has a regulatory function in cell cycle progression, signal transduction, and transcription. [8]
Cdh1 plays a pivotal role in controlling cell division at the end of mitosis and in the subsequent G1 phase of cell cycle: By recognizing and binding proteins (like mitotic cyclins) which contain a destruction box (D-box) and an additional degradation signal (KEN box), Cdh1 recruits them in a C-box-dependent mechanism to the APC for ubiquination and subsequent proteolysis.
In biochemistry, a ligase is an enzyme that can catalyze the joining of two molecules by forming a new chemical bond. This is typically via hydrolysis of a small pendant chemical group on one of the molecules, typically resulting in the formation of new C-O, C-S, or C-N bonds.