Protein
Niacin transporter NiaX
Organism
Lactococcus lactis subsp. cremoris (strain MG1363)
Function
Probably a niacin-binding protein that interacts with the energy-coupling factor (ECF) ABC-transporter complex. Unlike classic ABC transporters this ECF transporter provides the energy necessary to transport a number of different substrates. The substrates themselves are bound by transmembrane, not extracytoplasmic soluble proteins. Uptake of niacin into proteosomes containing EcfA1A2T and Niax has been demonstrated. Uptake requires hydrolyzable Mg-ATP and is substrate-specific; NiaX-containing proteosomes did not transport riboflavin.
Similarity
Belongs to the vitamin uptake transporter (VUT/ECF) (TC 2.A.88) family.
Sequence
MRNHDCPTVRFFKARVYKEKETQMTQTKKAKVRNLIIAAMLTALGILIPMMMPVKLIIGPASFTLAAHVPVMAAMFFSPLMTAFVALGTTLGFMISIPVPTIWLRALMHLPVMTVGAYVLKKYPEFVHQKVKIQIFNFILGIFHAGLETLVVYAFYSLGFANIEQGALLNFLLLIALGGLVHSMIDFNLALGLGNVLSKAFPIDIFDKAKNLVNKKKVKAEI