Background: Within the sulfotransferase (SULT) superfamily of metabolic enzymes,
SULT1A1 and 1A3/4 isoforms are of particular interest, due to their abilities to catalyze the sulfation
of phenolic endobiotics and xenobiotics. Although the difference in their substrate specificity is well
documented, an isoform-specific quantification method is still not available.
Objective: To detect and quantify SULT1A1 and 1A3/4 in S9 fractions and cell lines using targeted
mass spectrometry-based proteomics.
Method: Samples were tryptically digested, and signature peptides were quantified using liquid
chromatography- multiple reaction monitoring mass spectrometry (LC-MRM/MS). Stable isotopelabeled
(SIL) peptides were used as internal and calibration standards. SULT1A1 and SULT1A3/4
were quantified in various S9 fractions and cell line samples.
Results: Intraday and interday variabilities were low for relative quantification in S9 and cell line matrices
(<8%). Expression profiles were validated using Western blot analysis of S9 fractions and lentiviral
transduced SULT1A-overexpressing cell lines.
Conclusion: A reproducible method for simultaneous quantification of SULT1A1 and SULT1A3/4 in
S9 fractions and cell line samples was established and validated.