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3.A.1.106.18
Peptide and multidrug resistance porter of the ABC superfamily, TmrAB. TmrA (Q72J05; 600 aas with 6 N-terminal TMSs) and TmrB (Q72J04; 578 aas with 6 N-terminal TMSs) comprise this heterodimeric transporter, both proteins of the M-C structure.  The system has been found to export the dye, hoechst 33342, and to be inhibited by verapamil (Zutz et al. 2011). The subnanometre-resolution structure of detergent-solubilized TmrAB in a nucleotide-free, inward-facing conformation by single-particle electron cryomicroscopy has been solved (Kim et al. 2015). A cavity in the transmembrane domain is accessible laterally from the cytoplasmic side of the membrane as well as from the cytoplasm, indicating that the transporter lies in an inward-facing open conformation. The two nucleotide-binding domains remain in contact via their carboxy-terminal helices. Comparison between this structure and those of other ABC transporters suggests a possible trajectory of conformational changes that involves a sliding and rotating motion between the two nucleotide-binding domains during the transition from the inward-facing to outward-facing conformations (Kim et al. 2015). A subset of annular lipids is normally invariant in composition, with negatively charged lipids binding tightly to TmrAB, suggesting that this exporter may be involved in glycolipid translocation (Bechara et al. 2015). Coupled ATPase-adenylate kinase activity in ABC transporters including TmrAB has been demonstrated (Kaur et al. 2016). A 2.7-Å X-ray structure of TmrAB has been determined. It not only shares structural homology with the antigen translocation complex TAP, but is also able to restore antigen processing in human TAP-deficient cells. TmrAB exhibits a broad peptide specificity and can concentrate substrates several thousandfold, using only one single active ATP-binding site. It adopts an asymmetric inward-facing state, and the C-terminal helices, arranged in a zipper-like fashion, play a role in guiding the conformational changes associated with substrate transport (Nöll et al. 2017). Conformational coupling and trans-inhibition have been characterized (Barth et al. 2018).

Accession Number:Q72J04
Protein Name:Multidrug resistance ABC transporter ATP-binding and permease protein
Length:578
Molecular Weight:64554.00
Species:Thermus thermophilus (strain HB27 / ATCC BAA-163 / DSM 7039) [262724]
Number of TMSs:6
Substrate

Cross database links:

Structure:
5MKK   6RAF   6RAG   6RAH   6RAI   6RAJ   6RAK   6RAL   6RAM   6RAN   [...more]

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Predict TMSs (Predict number of transmembrane segments)
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FASTA formatted sequence
1:	MTGRSAAPLL RRLWPYVGRY RWRYLWAVLA GLVSIFFFVL TPYFLRLAVD AVQAGRGFGV 
61:	YALAIVASAA LSGLLSYAMR RLAVVASRQV EYDLRRDLLH HLLTLDRDFY HKHRVGDLMN 
121:	RLNTDLSAVR EMVGPGILMG SRLSFLVLLA FLSMYAVNAR LAFYLTLILP GIFLAMRFLL 
181:	RLIDRRYREA QEVFDRISTL AQEAFSGIRV VKGYALERRM VAWFQDLNRL YVEKSLALAR 
241:	VEGPLHALLG FLMGFAFLTV LWAGGAMVVR GELSVGELVQ FNAYLAQLTW PILGLGWVMA 
301:	LYQRGLTSLR RLFELLDEKP AIRDEDPLPL ALEDLSGEVR FEGVGLKRDG RWLLRGLTLT 
361:	IPEGMTLGIT GRTGSGKSLL AALVPRLLDP SEGRVYVGGH EARRIPLAVL RKAVGVAPQE 
421:	PFLFSETILE NIAFGLDEVD RERVEWAARL AGIHEEILAF PKGYETVLGE RGITLSGGQR 
481:	QRVALARALA KRPKILILDD ALSAVDAETE ARILQGLKTV LGKQTTLLIS HRTAALRHAD 
541:	WIIVLDGGRI VEEGTHESLL QAGGLYAEMD RLQKEVEA