Sandbox Reserved 812: Difference between revisions
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MsbA belongs to the '''ABC super-family''' of transporters and it is more specifically a member of the MDR (Multidrug resistance)-ABC transporter group by sequence homology. MsbA is more closely related to the mammalian [[P-glycoprotein]] than any other bacterial ABC transporter. | MsbA belongs to the '''ABC super-family''' of transporters and it is more specifically a member of the MDR (Multidrug resistance)-ABC transporter group by sequence homology. MsbA is more closely related to the mammalian [[P-glycoprotein]] than any other bacterial ABC transporter. | ||
<Structure load='3b5w' size='500' frame='true' align='right' caption='Structure of MsbA of E.Coli' scene=' | <Structure load='3b5w' size='500' frame='true' align='right' caption='Structure of MsbA of E.Coli' scene='56/568010/Default_scene/1' /> | ||
<scene name='56/568010/Default_scene/1'>(Default scene)</scene> | |||
==Structural organization of MsbA flippase== | ==Structural organization of MsbA flippase== | ||
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===Transmembrane domain=== | ===Transmembrane domain=== | ||
All the transmembrane α-helices are tilted between 30ᵒand 40ᵒ from the normal of the membrane, forming a cone shaped structure with two substantial openings on either side facing the lipid bilayer. These openings lead into a '''large cone-shaped chamber''' in the interior of the molecule's transmembrane domain. | All the <scene name='56/568010/Transmembrane_domains/1'>transmembrane α-helices</scene> are tilted between 30ᵒand 40ᵒ from the normal of the membrane, forming a cone shaped structure with two substantial openings on either side facing the lipid bilayer. These openings lead into a '''large cone-shaped chamber''' in the interior of the molecule's transmembrane domain. | ||
The primary role of the transmembrane domain is to recognize and transport substrates across the lipid bilayer. | The primary role of the transmembrane domain is to recognize and transport substrates across the lipid bilayer. | ||
The residues lining the proposed chamber opening (TM2, TM5, and TM6) play an important role in substrate recognition. | The residues lining the proposed chamber opening (TM2, TM5, and TM6) play an important role in substrate recognition. | ||
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===NBD structure=== | ===NBD structure=== | ||
The ABC is located in the NBD and couples the energy of ATP hydrolysis to substrate translocation. The NBD is the most conserved feature of the MDR-ABC transporter family and contains the Walker A/B motif along with the ABC signature motif. In the absence of ATP or nucleotide analog in this structure, residues 341 to 418, which includes the Walker A motif, are disordered in electron density maps. | The ABC is located in the <scene name='56/568010/Nbd/1'>NBD</scene> and couples the energy of ATP hydrolysis to substrate translocation. The NBD is the most conserved feature of the MDR-ABC transporter family and contains the Walker A/B motif along with the ABC signature motif. In the absence of ATP or nucleotide analog in this structure, residues 341 to 418, which includes the Walker A motif, are disordered in electron density maps. | ||
===ICD structure=== | ===ICD structure=== | ||
A distinctive feature of the MDR-ABC transporter family is two extensive intracellular regions called ICD1 (residues 97 to 139) ICD2 (residues 193 to 252) and ICD3 (residues 302 to 327). | A distinctive feature of the MDR-ABC transporter family is two extensive intracellular regions called <scene name='56/568010/Icd1/3'>ICD1</scene> (residues 97 to 139) <scene name='56/568010/Icd2/3'>ICD2</scene> (residues 193 to 252) and <scene name='56/568010/Icd3/2'>ICD3</scene> (residues 302 to 327). ICD1, which is sandwiched between ICD2 and the NBD, is composed of three α-helices connected by short loops to form a "U"-like structure. ICD3 links TM6 and the NBD and forms two α-helices connected by short loops. | ||
ICD1, which is sandwiched between ICD2 and the NBD, is composed of three α-helices connected by short loops to form a "U"-like structure. ICD3 links TM6 and the NBD and forms two α-helices connected by short loops. | |||
===Chamber structure=== | ===Chamber structure=== | ||