View source for BtuB

<StructureSection load='3m8d' size='450' side='right' scene='43/439262/Cv/1' caption='E. coli BtuB complex with cobalamin (a vitamin B12 derivative), lipid, methanesulfonothioate derivative and Ca+2 ions (green) (PDB code [[3m8d]])'>

== Function ==

'''BtuB''' or '''vitamin B12 receptor''' or '''outer membrane cobalamin transporter''' is an outer membrane receptor found in a variety of bacteria, such as ''E. coli''. BtuB transports vitamin B12 across the membrane of gram-negative bacteria.  The transport is achieved with high affinity by the collaboration of BtuB and the periplasmic protein TonB. <ref>PMID:14499604</ref> As an essential receptor for the cell that is constitutively expressed, it is an ideal target to be parasitized, a feature exploited by a variety of proteins such as [[Colicin]]s. 

== Structural highlights ==

BtuB depends on the presence of Ca+2 ions for high affinity <scene name='43/439262/Cv/6'>binding of cobalamin (a form of vitamin B12)</scene>.  The <scene name='43/439262/Cv/7'>Ca+2 ions are coordinated to several Asp side chains</scene>.<ref>PMID:20816073</ref>

==3D structure of BtuB==
[[BtuB 3D structures]]

</StructureSection>


== References ==
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