Function
Functions as retinol transporter (PubMed:23839944, PubMed:24852372). Accepts all-trans retinol from the extracellular retinol-binding protein RBP4, facilitates retinol transport across the cell membrane, and then transfers retinol to the cytoplasmic retinol-binding protein RBP1. Retinol uptake is enhanced by LRAT, an enzyme that converts retinol to all-trans retinyl esters, the storage forms of vitamin A (By similarity). Contributes to the activation of a signaling cascade that depends on retinol transport and LRAT-dependent generation of retinol metabolites that then trigger activation of JAK2 and its target STAT5, and ultimately increase the expression of SOCS3 and inhibit cellular responses to insulin (PubMed:21368206, PubMed:23839944). Important for the homeostasis of vitamin A and its derivatives, such as retinoic acid and 11-cis-retinal (PubMed:22467576, PubMed:24852372). STRA6-mediated transport is particularly important in the eye, and under conditions of dietary vitamin A deficiency (PubMed:22467576, PubMed:23839944, PubMed:24852372). Does not transport retinoic acid (By similarity).
Sequence
MESQASENGSQTSSGVTDDYSSWYIEEPLGAEEVQPEGVIPLCQLTAPPALLHACLASLSFLVLLLLALLVRRRRLWPRCGHRGLGLPSPVDFLAGDLSWTVPAAVFVVLFSNLCLLLPDENPLPFLNLTAASSPDGEMETSRGPWKLLALLYYPALYYPLAACASAGHQAAFLLGTVLSWAHFGVQVWQKAECPQDPKIYKHYSLLASLPLLLGLGFLSLWYPVQLVQSLRHRTGAGSQGLQTSYSEKYLRTLLCPKKLDSCSHPASKRSLLSRAWAFSHHSIYTPQPGFRLPLKLVISATLTGTATYQVALLLLVSVVPTVQKVRAGINTDVSYLLAGFGIVLSEDRQEVVELVKHHLWTVEACYISALVLSCASTFLLLIRSLRTHRANLQALHRGAALDLDPPLQSIHPSRQAIVSWMSFCAYQTAFSCLGLLVQQVIFFLGTTSLAFLVFVPLLHGRNLLLLRSLESTWPFWLTVALAVILQNIAANWIFLRTHHGYPELTNRRMLCVATFLLFPINMLVGAIMAVWRVLISSLYNTVHLGQMDLSLLPQRAASLDPGYHTYQNFLRIEASQSHPGVIAFCALLLHAPSPQPRPPLAPQDSLRPAEEEEGMQLLQTKDLMAKGAGHKGSQSRARWGLAYTLLHNPSLQAFRKAALTSAKANGTQP