Table 2.

The effect of residual structure in precursor proteins introduced by disulfide bridges on their import

Precursor protein					Import inhibition*
No. of strands imported in parallel	Position of crosslink by linked amino acids†				Outer membrane	Inner membrane
3	43–80				1.1  ± 0.1	1.6  ± 0.1
3		70–92			1.2  ± 0.1	1.3  ± 0.1
3			85–102		1.1  ± 0.1	1.6  ± 0.1
3	43–80	70–92			1.4  ± 0.1	2.0  ± 0.1
3		70–92	85–102		1.6  ± 0.1	1.3  ± 0.1
5	43–80		85–102		2.3  ± 0.1	9  ± 1
5	43–80	70–92	85–102		3.7  ± 0.3	16  ± 3
5	43–80	70–92	85–102	96–110	8.5  ± 0.5	13  ± 1

Import across the inner membrane was differentiated from import across the outer membrane by rupturing the outer membrane by osmotic shock before assaying for import. Values are calculated from data in ref. 5 and are shown as means ± SEM from at least three repeat experiments. 

^*Import rate constant of wild-type precursor divided by import rate constant of precursors containing disulfide bridges. 

^†Disulfide bond formation was induced with 10 mM K₃Fe(CN)₆.