formin family members have two adjacent domains:

FH1- rich in proline, landing site for profilin–ATP–G-actin

FH2 - form a dimer and nucleate filament assembly

TLS Online TPP Program

#Id: 8631

#XL - T Zoology

APC/C core is organized into three modules: 

1. a scaffold module 

2. a catalytic module

3. a substrate recognition module

TLS Online TPP Program

#Id: 8632

#XL - T Zoology

Substrate-targeting subunits of the APC/C recognize specific sequence motifs on the proteins that the APC/C ubiquitinates. One motif, the destruction box or D-box, has the consensus sequence

RXXLX[D/E]ΦΦΦXN[N/S]

TLS Online TPP Program

#Id: 8633

#XL - T Zoology

Mutating or deleting the destruction box in mitotic cyclins prevented their ubiquitination and blocked cells from exiting mitosis.

TLS Online TPP Program

#Id: 8634

#XL - T Zoology

At the metaphase to anaphase transition, APC/C bound to Cdc20 targets cyclins A /B and securin for degradation.

TLS Online TPP Program

#Id: 8635

#XL - T Zoology

During late anaphase, telophase and G1, APC/C bound to Cdh1 targets B type cyclins and geminin for degradation.

TLS Online TPP Program

#Id: 8637

#XL - T Zoology

The G1 cyclin-CDK complex (Cln3-CDK in yeast) stimulates the formation of G1/S phase cyclin-CDKs, which initiate bud formation, centrosome duplication, and DNA replication.