Protein targeting to different cellular destinations

13 Protein targeting to different cellular destinations





Questions



image How are proteins targeted to different cellular destinations?

image What is the signal for proteins to enter the secretory pathway?

image How are proteins destined for the endoplasmic reticulum prevented from being secreted?

Proteins are targeted to cellular destinations by specific structural signals within the protein or, in the absence of a specific signal, to a default destination. A complex series of primary and/or secondary structural protein motifs together with appropriate receptor proteins in the target organelle play major roles. Compartment-specific retention signals are also important so that protein activities localized to particular compartments are not randomized during interorganelle vesicular transport.



Secretory pathways


Nascent polypeptides from the rough ER pass initially to the Golgi apparatus (Fig. 3.13.1). Some proteins are arrested by specific targeting signals that locate the protein within the secretory pathway (e.g. protein disulphide isomerase to the ER, glycosyl transferases to the Golgi) (Fig. 3.13.2). A C-terminal does not carry a specific address. The constitutive pathway is Ca2+ dependent. The Ca2+

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Jun 18, 2016 | Posted by in BIOCHEMISTRY | Comments Off on Protein targeting to different cellular destinations

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