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2.A.125 The Eukaryotic Riboflavin Transporter (E-RFT) Family

Human and rat plasma membrane riboflavin transporters, hRFT1 and rRFT1, were identified on the basis of a rat kidney mRNA expression database (Horiba et al. 2004). hRFT1 and rRFT1 cDNAs have an open reading frame encoding 448- and 450-amino acid proteins, respectively. Overexpression of hRFT1 or rRFT1 increased the cellular accumulation of [(3)H]riboflavin (Yonezawa et al. 2008). The transfection of small interfering RNA targeting both hRFT1 and hRFT1sv significantly decreased the uptake of [(3)H]riboflavin by HEK-293 and Caco-2 cells. Riboflavin (Km ≈ 40μM) transport is Na+, potential, and pH independent. RFT1 shows low similarity with the TRAP-T porters (2.A.56), nucleoside transporters (2.A.57) and aromatic acid porters (2.A.1.15).

The generalized reaction catalyzed by RFT1 is:

riboflavin (out) ⇌ riboflavin (in)

This family belongs to the: Major Facilitator (MFS) Superfamily.

References associated with 2.A.125 family:

Horiba, N., S. Masuda, A. Takeuchi, H. Saito, M. Okuda, and K. Inui. (2004). Gene expression variance based on random sequencing in rat remnant kidney. Kidney Int 66: 29-45. 15200410
O''Callaghan, B., A.M. Bosch, and H. Houlden. (2019). An update on the genetics, clinical presentation, and pathomechanisms of human riboflavin transporter deficiency. J Inherit Metab Dis. [Epub: Ahead of Print] 30793323
Sabui, S., V.S. Subramanian, Q. Pham, and H.M. Said. (2019). Identification of transmembrane protein 237 as a novel interactor with the intestinal riboflavin transporter-3 (RFVT-3): role in functionality and cell biology. Am. J. Physiol. Cell Physiol. [Epub: Ahead of Print] 30892938
Wolf, C.J.H., H. Venselaar, M. Spoelder, H. Beurmanjer, A.F.A. Schellekens, and J.R. Homberg. (2023). An Overview of the Putative Structural and Functional Properties of the GHBh1 Receptor through a Bioinformatics Approach. Life (Basel) 13:. 37109455
Yonezawa, A. and K. Inui. (2013). Novel riboflavin transporter family RFVT/SLC52: identification, nomenclature, functional characterization and genetic diseases of RFVT/SLC52. Mol Aspects Med 34: 693-701. 23506902
Yonezawa, A., S. Masuda, T. Katsura, and K. Inui. (2008). Identification and functional characterization of a novel human and rat riboflavin transporter, RFT1. Am. J. Physiol. Cell Physiol. 295: C632-641. 18632736