Stroke & Vascular Disorders
Ischemic stroke syndromes and their anatomic localization
Aug. 23, 2023
This is an image preview.
Start a Free Account
to view the full image.
-
Nearly 3,000 illustrations, including video clips of neurologic disorders.
-
Every article is reviewed by our esteemed Editorial Board for accuracy and currency.
-
Full spectrum of neurology in 1,200 comprehensive articles.
-
Listen to MedLink on the go with Audio versions of each article.
Renal reabsorption of folates from glomerular filtrate
Renal reabsorption of folates from glomerular filtrate in the proximal tubules under physiological conditions is thought to rely on the high-affinity folate receptor FRα through a process of transcytosis to the basolateral membrane into the blood. The multifunctional endocytic receptors megalin, which binds soluble folate binding proteins (FBP), and cubilin, which binds albumin (ALB), may also be involved in the uptake of folates under conditions of folate deficiency. The folate-specific transporters reduced folate carrier (RFC) and proton-coupled folate transported (PCFT) are highly expressed in the proximal renal tubule, with known expression of RFC at the basolateral membrane. Additional low-affinity, high-capacity folate transporters expressed at the apical membrane include the multidrug resistance-associated protein (MRP) efflux pumps 2 and 4 (MRP2 and MRP4) and the organic anion transporters (OAT) K1, K2, and 4. At the basolateral membrane, OAT1, OAT2, and OAT3 as well as the efflux pump MRP3 may contribute to renal folate transport.
Legend: ALB: albumin; FBP: folate binding protein; FRα: folate receptor alpha; MRP: multidrug resistance-associated protein; OAT: organic anion transporters; PCFT: proton-coupled folate transporter; RFC: reduced folate carrier. (Source: Shulpekova Y, Nechaev V, Kardasheva S, et al. The concept of folic acid in health and disease. Molecules 2021;26(12):3731.) (Modified by Dr. Douglas Lanska. Creative Commons Attribution 4.0 [CC BY] license.)