Table I.

Amino acid uptake into SHR3 , shr3 ΔCT, and shr3 Δ null mutant strains

Substratea	SHR3	shr3ΔCT	shr3Δ	shr3ΔCT/SHR3
	units b	units	units	ratio
Glutamate	0.230	0.075	0.008	0.33
Proline	0.075	0.043	0.001	0.57
Leucinec	1.40	0.784	0.052	0.56
Phenylalaninec	1.34	0.705	0.019	0.53

^aInitial rates of uptake were determined in SUD-grown strain JKY1 carrying either pPL210 (SHR3), pJK36 (shr3ΔCT), or pRS316 (shr3Δ) at a substrate concentration of 4 μM in buffer containing 2% glucose (Martínez and Ljungdahl, 2000). Uniformly, ¹⁴C-labeled l-amino acids were obtained from Amersham Biosciences. Subsamples were removed at 30, 60, and 180 s; the rates of glutamate and proline were linear throughout the subsampling period.

^bUnit = nmol min⁻¹ mg⁻¹ dry weight.

^cApproximate rate based on single point measurements at the 30-s time point.