Recombinant Clostridium botulinum Botulinum neurotoxin type F (botF), partial

Function

Responsible for host epithelial cell transcytosis, host nerve cell targeting and translocation of light chain (LC) into host cytosol. Composed of 3 subdomains; the translocation domain (TD), and N-terminus and C-terminus of the receptor-binding domain (RBD). The RBD is responsible for the adherence of the toxin to the cell surface. It simultaneously recognizes 2 coreceptors; polysialated gangliosides and the receptor protein SV2A, SV2B and SV2C in close proximity on host synaptic vesicles; although not all evidence indicates these are the receptors (By similarity). The N-terminus of the TD wraps an extended belt around the perimeter of the LC, protecting Zn(2+) in the active site; it may also prevent premature LC dissociation from the translocation channel and protect toxin prior to translocation (By similarity). The TD inserts into synaptic vesicle membrane to allow translocation into the host cytosol (By similarity)

Subcellular Location

Secreted; Host synapse, host presynaptic cell membrane; Host cytoplasmic vesicle, host secretory vesicle, host synaptic vesicle membrane (Multi-pass membrane protein)

Subunit

Heterodimer; disulfide-linked heterodimer of a light chain (LC) and a heavy chain (HC). The LC has the proteolytic/pharmacological activity, while the N- and C-terminal of the HC mediate channel formation and toxin binding, respectively. Interacts with host synaptic vesicle glycoproteins SV2A, SV2B and SV2C (By similarity)

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