Table 2.

Rules for model construction

1. Should reflect known physical interactions between ESCRT components

2. ESCRTs should assemble in order but need not act strictly linearly

3. Should consider the membrane area required to form a vesicle of appropriate size

4. Should consider spatial requirements on the basis of known ESCRT structures

5. Should selectively incorporate MVB cargoes

6. Deubiquitylation should precede or coincide with vesicle formation

7. ESCRT-II should be able to compensate for the loss of ESCRT-I in yeast

8. ESCRT-III dissociation is not required for MVB vesicle formation

9. Should allow bypass of Ub-dependent cargo-sorting mechanism

ESCRT, endosomal sorting complex required for transport; MVB, multivesicular body; Ub, ubiquitin