ELM - Detail for LIG_APCC_Cbox

Accession:	ELME000349
Functional site class:	APC/C_Apc2-docking motif
Functional site description:	The Anaphase Promoting Complex or Cyclosome (APC/C) E3 ubiquitin ligase controls progression through the cell cycle by ubiquitylation of cell cycle regulators, which are subsequently degraded by the proteasome. The catalytic activity and substrate specificity of the APC/C depends on its association with the co-activator proteins such as Cdc20 and Cdh1, which recognize short destruction motifs present in APC/C substrates (including LIG_APCC_Dbox_1 and LIG_APCC_KENbox_2 degrons). By binding to these motifs, the co-activator mediates recruitment of substrates to the APC/C, which catalyzes their ubiquitylation. The co-activators themselves bind to the APC/C core via their C-box motif, a short, highly conserved motif that possibly interacts with the catalytic Apc2 subunit. Experimental evidence indicates that the C-box is essential for Cdc20 function and proteolysis of Clb2 by Cdh1, and is possibly involved in stimulating the catalytic activity of the APC/C.
ELMs with same func. site:	LIG_APCC_Cbox_1 LIG_APCC_Cbox_2
ELM Description:	The C-box motif is located in the N-terminal region of APC/C co-activators and is conserved among Cdc20-related proteins in Bacteria759. It mediates binding of the co-activators to the APC/C core, possibly to the catalytic Apc2 subunit. Removal of C-box from Cdh1 disrupts the ability of Cdh1 to trigger Clb2 proteolysis and overexpression of mutant Cdh1 lacking the C-box-containing region does not affect cell proliferation. Especially the residue in the second motif position, which is invariantly occupied by an arginine residue, seems to be important for binding Cdh1 to the APC/C in vitro and for APC/C function in vivo (Thornton,2006). Similarly, the C-box motif in Cdc20 was shown to be essential for proper protein function. Also, the arginine in the second position of the Cdc20 C-box is essential for motif function and seems to be crucial for viability as the charge-swap mutation of this residue is lethal (Thornton,2006). The binding site of the C-box on the APC/C has not yet been identified, but some evidence suggests that it might interact with the catalytic Apc2 subunit (Matyskiela,2009). This supports the idea that the APC/C co-activators to the APC/C are not only important for substrate recruitment, but are also involved in activating the catalytic activity of the complex, possibly through the interaction of their C-box motif with the APC/C catalytic core. This second variant of the motif is defined for Fungi and Amoebozoa, which have a less stringent motif definition due to less conservation of the last residue of the motif sequence. In most Bacteria759, this residue is invariantly an arginine (DEG_APCC_Cbox_1), while in Fungi and Amoebozoa, this position also allows other residues, mainly but not exclusively hydrophobic ones. In addition, the glutamate in the first position observed for some flies and the glycine in the fifth position observed for some worms are not defined in this variant.
Pattern:	`DR[YFH][ILFVM][PA]..`
Pattern Probability:	`0.0000058`
Present in taxons:	Amoebozoa Fungi
Interaction Domain:	TPR_1 (PF00515) Tetratricopeptide repeat (Stochiometry: 1 : 1)

APC/C_Apc2-docking motif

The Anaphase Promoting Complex or Cyclosome (APC/C) E3 ubiquitin ligase controls progression through the cell cycle by ubiquitylation of cell cycle regulators, which are subsequently degraded by the proteasome. The catalytic activity and substrate specificity of the APC/C depends on its association with the co-activator proteins such as Cdc20 and Cdh1, which recognize short destruction motifs present in APC/C substrates (including LIG_APCC_Dbox_1 and LIG_APCC_KENbox_2 degrons). By binding to these motifs, the co-activator mediates recruitment of substrates to the APC/C, which catalyzes their ubiquitylation. The co-activators themselves bind to the APC/C core via their C-box motif, a short, highly conserved motif that possibly interacts with the catalytic Apc2 subunit. Experimental evidence indicates that the C-box is essential for Cdc20 function and proteolysis of Clb2 by Cdh1, and is possibly involved in stimulating the catalytic activity of the APC/C.

ELMs with same func. site:

LIG_APCC_Cbox_1 LIG_APCC_Cbox_2

ELM Description:

The C-box motif is located in the N-terminal region of APC/C co-activators and is conserved among Cdc20-related proteins in Bacteria759. It mediates binding of the co-activators to the APC/C core, possibly to the catalytic Apc2 subunit. Removal of C-box from Cdh1 disrupts the ability of Cdh1 to trigger Clb2 proteolysis and overexpression of mutant Cdh1 lacking the C-box-containing region does not affect cell proliferation. Especially the residue in the second motif position, which is invariantly occupied by an arginine residue, seems to be important for binding Cdh1 to the APC/C in vitro and for APC/C function in vivo (Thornton,2006). Similarly, the C-box motif in Cdc20 was shown to be essential for proper protein function. Also, the arginine in the second position of the Cdc20 C-box is essential for motif function and seems to be crucial for viability as the charge-swap mutation of this residue is lethal (Thornton,2006). The binding site of the C-box on the APC/C has not yet been identified, but some evidence suggests that it might interact with the catalytic Apc2 subunit (Matyskiela,2009). This supports the idea that the APC/C co-activators to the APC/C are not only important for substrate recruitment, but are also involved in activating the catalytic activity of the complex, possibly through the interaction of their C-box motif with the APC/C catalytic core. This second variant of the motif is defined for Fungi and Amoebozoa, which have a less stringent motif definition due to less conservation of the last residue of the motif sequence. In most Bacteria759, this residue is invariantly an arginine (DEG_APCC_Cbox_1), while in Fungi and Amoebozoa, this position also allows other residues, mainly but not exclusively hydrophobic ones. In addition, the glutamate in the first position observed for some flies and the glycine in the fifth position observed for some worms are not defined in this variant.

Pattern:

DR[YFH][ILFVM][PA]..

Pattern Probability:

0.0000058

Present in taxons:

Amoebozoa Fungi

Interaction Domain:

TPR_1 (PF00515) Tetratricopeptide repeat (Stochiometry: 1 : 1)

The ubiquitylation pathway plays an important role in cell division as it mediates progression of the cell cycle by sequential targeting of important cell cycle regulators for proteasomal degradation. There are two E3 ubiquitin protein ligase complexes that regulate the cell cycle: the SCF (Skp1/Cullin/F-box) complex and the anaphase-promoting complex or cyclosome (APC/C) (Peters,2006, Castro,2005). The APC/C is a multiprotein complex that contains at least 13 different subunits, most of which are conserved in Eukaryotes. It consists of two subcomplexes that associate independently with the largest subunit Apc1. One is the catalytic core subcomplex that includes the cullin domain-containing subunit Apc2 and the RING domain-containing subunit Apc11. The second subcomplex mainly consists of tetratricopeptide repeat (TPR) domain-containing proteins including the Apc3/Cdc27, Apc8/Cdc23, Apc6/Cdc16, Apc5 and Apc7 subunits (Labit,2012). Several of the TPR-containing subunits form homodimers and are thus present in two copies in a single APC/C complex (Barford,2011, Primorac,2013).
Specific ubiquitylation of substrates requires association of the APC/C with a co-activator such as Cdc20/Fizzy or Cdh1/Fizzy-related, which are active at distinct phases of the cell cycle. These co-activators function as substrate-recruitment factors of the APC/C. They contain WD40 domain repeats, well known motif-binding modules that are folded as a 7-bladed beta-propeller. The WD40 repeats of APC/C co-activators recognize target proteins via short degradation motifs or degrons present in APC/C substrates. Well characterised degrons are the D-box (LIG_APCC_Dbox_1) and KEN-box (LIG_APCC_KENbox_2) motifs, which bind to distinct sites on the WD40 domain and are thought to preferentially interact with Cdc20 and Cdh1, respectively. However, efficient recruitment to and ubiquitylation by the APC/C likely depends on cooperative binding of multiple motifs (Chao,2012). In addition to substrate recognition, these co-activators are also required for activation of the ubiquitylation activity of the APC/C (Hayes,2006).
Binding of the co-activators to the APC/C is also mediated by multiple motifs, allowing multivalent cooperative binding (Matyskiela,2009). A Cdc20-specific motif has been described as a site for binding to the APC/C, possibly via the Apc8/Cdc23 subunit, and related to the specific role of this co-activator in the Spindle Assembly Checkpoint (SAC) (Izawa,2012). Both Cdc20 and Cdh1 share a C-terminal IR motif (LIG_APCC_TPR_1) that binds to the TPR repeats of the Apc3/Cdc27 subunit (Vodermaier,2003). In addition, both co-activators contain an internal C-box motif (LIG_APCC_Cbox_1 and LIG_APCC_Cbox_2), located in the N-terminal region, that most likely binds to the Apc2 subunit, and hence is possibly involved in stimulating the catalytic activity of the APC/C (da Fonseca,2011).

Biological Process:
Anaphase-Promoting Complex-Dependent Proteasomal Ubiquitin-Dependent Protein Catabolic Process (also annotated in these classes: )
Cell Cycle Phase Transition (also annotated in these classes: )
Activation Of Anaphase-Promoting Complex Activity (also annotated in these classes: )
Cellular Compartment:
Anaphase-Promoting Complex (also annotated in these classes: )
Nucleus (also annotated in these classes: )
Cytosol (also annotated in these classes: )
Molecular Function:
Ubiquitin-Protein Ligase Activity (also annotated in these classes: )
Protein Binding (also annotated in these classes: )

Acc., Gene-, Name	Start	End	Subsequence	Logic	#Ev.	Organism
P26309 CDC20 CDC20_YEAST	144	150	QFTVAADRYIPILQGASQNK	TP	3	Saccharomyces cerevisiae (Baker"s yeast)
P53197 CDH1 CDH1_YEAST	55	61	PSTVYGDRYIPSRTDIDFNS	TP	7	Saccharomyces cerevisiae S288c
P50082 AMA1 AMA1_YEAST	29	35	GNSTEVDRFIPKSVSRNAYK	TP	2	Saccharomyces cerevisiae S288c

Acc., Gene-, Name

Start

End

Subsequence

Logic

#Ev.

Organism

Notes

P26309 CDC20
CDC20_YEAST

144

150

QFTVAADRYIPILQGASQNK