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1) The signal
peptide is cleaved within lumen by signal
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peptidase
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2) BiP (a
chaperonin) helps protein fold correctly.
It is a
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member of the
HSP70 family of heat shock proteins.
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When bound to ATP
it is in the open state and weakly
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binds to target
protein. But with the help of HSP40
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proteins it
hydrolyzes ATP to ADP. This leads to
a
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conformational
change that causes Bip to clamp tightly
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to hydorphobic
regions of the protein. This
processs is
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repeated over
and over until protein is folded into its final
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form.
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3) protein is
soluble inside lumen where it can be further
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modified
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