>TIGR02138 phosphate_pstC phosphate ABC transporter, permease protein PstC; InterPro: IPR011864 ABC transporters belong to the ATP-Binding Cassette (ABC) superfamily, which uses the hydrolysis of ATP to energize diverse biological systems. ABC transporters are minimally constituted of two conserved regions: a highly conserved ATP binding cassette (ABC) and a less conserved transmembrane domain (TMD). These regions can be found on the same protein or on two different ones. Most ABC transporters function as a dimer and therefore are constituted of four domains, two ABC modules and two TMDs. ABC transporters are involved in the export or import of a wide variety of substrates ranging from small ions to macromolecules. The major function of ABC import systems is to provide essential nutrients to bacteria. They are found only in prokaryotes and their four constitutive domains are usually encoded by independent polypeptides (two ABC proteins and two TMD proteins). Prokaryotic importers require additional extracytoplasmic binding proteins (one or more per systems) for function. In contrast, export systems are involved in the extrusion of noxious substances, the export of extracellular toxins and the targeting of membrane components. They are found in all living organisms and in general the TMD is fused to the ABC module in a variety of combinations. Some eukaryotic exporters encode the four domains on the same polypeptide chain . The ABC module (approximately two hundred amino acid residues) is known to bind and hydrolyze ATP, thereby coupling transport to ATP hydrolysis in a large number of biological processes. The cassette is duplicated in several subfamilies. Its primary sequence is highly conserved, displaying a typical phosphate-binding loop: Walker A, and a magnesium binding site: Walker B. Besides these two regions, three other conserved motifs are present in the ABC cassette: the switch region which contains a histidine loop, postulated to polarize the attaching water molecule for hydrolysis, the signature conserved motif (LSGGQ) specific to the ABC transporter, and the Q-motif (between Walker A and the signature), which interacts with the gamma phosphate through a water bond. The Walker A, Walker B, Q-loop and switch region form the nucleotide binding site , , . The 3D structure of a monomeric ABC module adopts a stubby L-shape with two distinct arms. ArmI (mainly beta-strand) contains Walker A and Walker B. The important residues for ATP hydrolysis and/or binding are located in the P-loop. The ATP-binding pocket is located at the extremity of armI. The perpendicular armII contains mostly the alpha helical subdomain with the signature motif. It only seems to be required for structural integrity of the ABC module. ArmII is in direct contact with the TMD. The hinge between armI and armII contains both the histidine loop and the Q-loop, making contact with the gamma phosphate of the ATP molecule. ATP hydrolysis leads to a conformational change that could facilitate ADP release. In the dimer the two ABC cassettes contact each other through hydrophobic interactions at the antiparallel beta-sheet of armI by a two-fold axis , , , , , . Proteins known to belong to this family are classified in several functional subfamilies depending on the substrate used (for further information see http://www.tcdb.org/tcdb/index.php?tc=3.A.1). The typical operon for the high affinity inorganic phosphate ABC transporter encodes an ATP-binding protein, a phosphate-binding protein, and two permease proteins. This family describes PstC, which is homologous to PstA (IPR005672 from INTERPRO). In the Escherichia coli, this transport system is induced when the concentration of extrallular inorganic phosphate is low. A constitutive, lower affinity transporter operates otherwise.; GO: 0005315 inorganic phosphate transmembrane transporter activity, 0006817 phosphate transport, 0016021 integral to membrane.

Probab=99.78  E-value=3e-15  Score=127.10  Aligned_cols=158  Identities=15%  Similarity=0.197  Sum_probs=138.0

Q ss_pred             HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHC--CHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHC-----------
Q ss_conf             06899999999999999999999999999999715--02678999999999743289999999999840-----------
Q gi|255764497|r   59 HSLPQYASRTTLRMLSAMVISLLFTFVYATLAAKS--RRLGMVLVPILDIMQSIPILGFLTFTVVYFMN-----------  125 (587)
Q Consensus        59 ~~l~~~~~~Tl~~~~~~~~~~~~ig~~~a~~~~~~--~~~~~~~~~~l~~~~~iP~~~~~~~~~~~f~~-----------  125 (587)
T Consensus        67 yG~l~~i~GTl~~~~~A~liA~P~~i~~Aif~~e~aP~~~~~~l~~~~ELLAgIPSVvYG~wG~~~l~P~l~~~~~~~~~  146 (317)
T TIGR02138        67 YGALPLIVGTLITSLIAILIAVPVGIGIAIFLSEIAPKRVKSVLKPVVELLAGIPSVVYGFWGLFVLVPFLKDHFQPFLG  146 (317)
T ss_pred             HHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHCCHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHHH
T ss_conf             56699999999999999999999999999999985251135699999999722359999999999999999998867865


Q ss_pred             -CC-----------CCCCCHHHHHHHHHHHHHHHHHHHHHHHHHHHHCCHHHHHHHHHCCCCCHHHHHHHHHHHHHHHHH
Q ss_conf             -14-----------554210479999999998535999999999972998999999962888201236555262157899
Q gi|255764497|r  126 -LY-----------PGKVIGAELAAIFAIFTSQVWNMTFSMYQSLCNIPRDLEEVSRSFRLSGWQKFWYLGVPFSMPGLV  193 (587)
Q Consensus       126 -~~-----------~~~~~~~~~~~i~~~~~~~~~~i~~~~~~~l~~i~~~l~eaa~~~Ga~~~~~f~~v~lP~~~P~i~  193 (587)
T Consensus       147 ~~~~~iP~~~~~~~~~~~G~~~L~a~~vL~IMIlPt~as~s~D~~~~VP~~~kea~~ALGAT~wetI~~v~lP~a~~GIv  226 (317)
T TIGR02138       147 SNFGWIPLFGQLFSGPPNGYGLLTAGIVLAIMILPTIASISRDALRAVPRSYKEASLALGATKWETIRKVILPAARSGIV  226 (317)
T ss_pred             HHCCCCCCCCCCCCCCCCHHHHHHHHHHHHHHHHHHHHHHHHHHHHHCCHHHHHHHHHHCCCHHHHHHHHHHHHHHHHHH
T ss_conf             31353232122368998316899999999999999999999999973556788898770686043355533200021899


Q ss_pred             HHHHHHHHHHHHHHHHHHHHHCC
Q ss_conf             99999999998998999997354
Q gi|255764497|r  194 WNMMMSMSGGWFFVVASEMIVVG  216 (587)
Q Consensus       194 ~~~~l~~~~~~~~~~~~~~~g~~  216 (587)
T Consensus       227 ~a~~LglGRAlGETmAV~mv~Gn  249 (317)
T TIGR02138       227 GAVVLGLGRALGETMAVAMVIGN  249 (317)
T ss_pred             HHHHHHHHHHHHHHHHHHHHHCC
T ss_conf             99999999999999999999724