Fig. 1.

Fucci probes with different ubiquitination domains of human Cdt1

(A) Fucci(SA) consists of an SCF^Skp2-sensitive hCdt1-based probe and an APC^Cdh1-sensitive hGem-based probe. Fucci(SA) corresponds to the original Fucci. A blue box in hCdt1(30/120) indicates the Cy motif.

(B) Fucci(CA) consists of a CUL4^Ddb1-sensitive hCdt1-based probe and an APC^Cdh1-sensitive hGem-based probe. The dark red box and the gray box in hCdt1(1/100)Cy(–) indicates the PIP box and Cy(–): mutated Cy motif , respectively.

(A, B) Domain structures (top) and cell-cycle phasing capabilities (bottom) are shown, assuming that the hCdt1- and hGem-based domains are fused to red- and green-emitting FPs. A theoretical temporal profile of the fluorescence intensity (F.I.) is shown below each domain structure. SCF, SCF^Skp2; CUL4, CUL4^Ddb1; APC, APC^Cdh1. Pink and black boxes in hGem(1/110) indicate the destruction box and nuclear localization signal, respectively. NEB: nuclear envelope breakdown. NER: re-formation of the nuclear envelope.