TABLE 1.

Transport and regulatory properties of MalK mutants

Plasmid	Allele	Protein synthesized	Maltose uptakea (%)	Repressing activityb (Miller units)
pSE380			0	159
pSW7	malK+	Wild type	100	11
pSH17-N41	malK820	L86F mutant	2	23
pSH17-N7	malK822	E306K mutant	4	15
pSH17-N18	malK824	P160L mutant	1	20
pSH17-N24	malK825	D65N mutant	2	16

^aCells of strain ES25 transformed with the described plasmids were grown at 37°C in the absence of isopropyl-β-d-thiogalactopyranoside (IPTG). The control value (100%) corresponds to 1.3 nmol min⁻¹ 10⁹ cells⁻¹. Data are the averages of at least two experiments. 

^bCells of strain SK1280 transformed with the described plasmids were grown in the presence of IPTG to mid-log phase, harvested, and prepared for β-galactosidase assay according to references 8 and 13. Data are the averages of two independent experiments.