TABLE 1

Summary of proteospecific peptides and their respective MRM transitions used for renal organic cation transporter protein quantification with LC-MS/MS

		MRM Transition (m/z)^{^a}
Protein	Peptide	Mass	Q1	Q3.1	Q3.2	Q3.3
		Da
OCT2	SLPASLQR	871	436	672	574	503
OCT2	SLPASLQR^{^c}	881	441	682	584	513
MATE1^{^b}	GGPEATLEVR	1027	515	688	617	458
MATE1^{^b}	GGPEATLEVR^{^c}	1037	520	698	627	463
MATE2K	YLQNQK	792	397	630	517	389
MATE2K	YLQNQK^{^c}	800	401	638	525	397

↵^a Theoretical m/z value of doubly charged ions of intact peptide (Q1) assumed as precursor ions and singly charged fragment ions derived from precursor ion indicated as Q3.1, Q3.2, and Q3.3.
↵^b There is a difference of one amino acid in the MATE1 peptide between species (human versus monkey: GGPEATLEVR versus GGPEATLELR). The expression level of cMATE1 was calculated by using human MATE1 standard.
↵^c The labeling of Arg (R) or Lys (K) was done by introducing the stable isotope ([¹³C] or [¹⁵N]).