Cell biology of the human thiamine transporter-1 (hTHTR1): Intracellular trafficking and membrane targeting mechanisms

Veedamali S. Subramanian, Jonathan S. Marchant, Ian Parker, Hamid M. Said

Research output: Contribution to journalArticlepeer-review

59 Scopus citations


The human thiamine transporter hTHTR1 is involved in the cellular accumulation of thiamine (vitamin B1) in many tissues. Thiamine deficiency disorders, such as thiamine-responsive megaloblastic anemia (TRMA), which is associated with specific mutations within hTHTR1, likely impairs the functionality and/or intracellular targeting of hTHTR1. Unfortunately, nothing is known about the mechanisms that control the intracellular trafficking or membrane targeting of hTHTR1. To identify molecular determinants involved in hTHTR1 targeting, we generated a series of hTHTR1 truncations fused with the green fluorescent protein and imaged the targeting and trafficking dynamics of each construct in living duodenal epithelial cells. Whereas the full-length fusion protein was functionally expressed at the plasma membrane, analysis of the truncated mutants demonstrated an essential role for both NH2-terminal sequence and the integrity of the backbone polypeptide for cell surface expression. Most notably, truncation of hTHTR1 within a region where several TRMA truncations are clustered resulted in intracellular retention of the mutant protein. Finally, confocal imaging of the dynamics of intracellular hTHTR1 vesicles revealed a critical role for microtubules, but not microfilaments, in hTHTR1 trafficking. Taken together, these results correlate hTHTR1 structure with cellular expression profile and reveal a critical dependence on hTHTR1 backbone integrity and microtubule-based trafficking processes for functional expression of hTHTR1.

Original languageEnglish (US)
Pages (from-to)3976-3984
Number of pages9
JournalJournal of Biological Chemistry
Issue number6
StatePublished - Feb 7 2003
Externally publishedYes


Dive into the research topics of 'Cell biology of the human thiamine transporter-1 (hTHTR1): Intracellular trafficking and membrane targeting mechanisms'. Together they form a unique fingerprint.

Cite this