Figure 3.

The cartoon depicts the handling of organic anion HGA in the hepatocyte. HGA accumulates due to lack of HGD enzyme (denoted by the green X). We propose that HGA can be eliminated via multidrug resistance-associated proteins (MRP, ABCC family of transporters) both into the biliary canaliculi as well as into the hepatic sinusoidal blood supported by the presence of these organic anion transporters at both these sites. HGA reaching the hepatic sinusoidal blood can be carried around the body before excretion by the kidney into the urine. PHE, TYR, HPPA and HGA represent phenylalanine, tyrosine, 4-hydroxyphenylpyruvate and homogentisate.