Table 3. Mean shrinkage rates of GDP MTs.

	ATP (μM)	Fast (plus) end (nm s−1±s.e.m. (n))	Slow (minus) end (nm s−1±s.e.m. (n))
A-lattice (Mal3FL)	0	10.68±0.30 (5)	2.78±0.42 (5)
B-lattice	0	2.68±0.73 (5)	0.34±0.13 (5)
B-lattice	1	55.14±5.12 (5)	7.06±2.82 (5)

Mean shrinkage rates of GDP MTs held in a rigor kinesin clamp were compared before and after the release of the clamp by addition of 1 μM ATP. The shrinkage at the plus end was 29 times faster in the A-lattice enriched microtubules and significantly different from the B-lattice (t-test, P<0.0001). The slow ends of A-lattice-enriched MTs also shrank significantly faster than in the B-lattice MTs by 8 times (t-test with Welch’s correction for unequal variances, P=0.0054).