Table 1

	fmol / µg membrane protein (%CV)^b			Apparent Ratio^c
Conditions^a	OATP1B1	OATP1B3	OATP2B1	1B1 : 1B3 : 2B1
ABC	210.1 ± 4.9 (5.7)	33.0 ± 1.3 (7.7)	39.5 ± 0.9 (5.4)	5.3 : 0.8 : 1
ABC + Gdn	42.9 ± 1.8 (10.2)	4.1 ± 0.1 (5.1)	23.5 ± 0.4 (4.2)	1.8 : 0.2 : 1
ABC + PMAX	299.8 ± 14.9 (12.2)	66.5 ± 3.9 (11.7)	36.7 ± 0.8 (5.5)	8.2 : 1.8 : 1
ABC + DOC	367.2 ± 8.1 (5.4)	137.2 ± 4.7 (6.8)	43.3 ± 1.3 (7.2)	8.4 : 3.2 : 1

^aMembrane fractions were initially denatured in 25 mM ABC alone or 25 mM ABC containing 7 M Gdn, 0.2% PMAX, or 10% DOC prior to alkylation, dilution, and digestion.
^bData represent the mean ± S.E.M. and coefficient of variation (CV%) for three transitions measured for each peptide by LC-MS/MS for 44 hr digestions processed in duplicate. Samples were processed from the same initial pellet for each transfected cell line to rule out variability in starting material.
^cThe apparent ratio between cell lines is provided to demonstrate how preparation conditions have a differential impact on the quantification of different proteins and thus alter the apparent ratio that is observed between different proteins.

Table 1: Quantification of OATP1B1 (surrogate-1), OATP1B3 (surrogate-2), and OATP2B1 (surrogate-1) peptides in transfected cell line membrane fractions under different sample preparation conditions.