Proteins Are Targeted to Their Destination by Signal Sequences

Proteins Are Targeted to Their Destination by Signal Sequences 

Despite the apparent complexity of the problem, protein transport in all systems is accomplished by a single, rather simple underlying mechanism each polypeptide destined 

Signal sequences usually occur at the amino terminus of polypeptides to be transported. These sequences vary in length from 10 to 40 amino acid residues and are generally characterized by the occurrence of a block of hydrophobic residues. The presence of hydrophobic residues reflects the fact that protein transport invariably involves the movement of proteins across lipid membranes. The hydrophobic residues both target the protein to the appropriate compartment and initiate penetration into the membrane. 

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Many proteins are targeted to their destinations by signal sequences. A major sorting decision is made when proteins are partitioned between cytosohc and membrane-bound polyribosomes by virtue of the absence or presence of a signal peptide. 

Targeting and Posttranslational Modification of Proteins Proteins Are Targeted to Their Destination by Signal Sequences... 

Proteins are targeted to their destination by signal sequences built into the polypeptide chain. These signals are usually located at the N-terminal end of the protein and are generally cleaved during protein maturation. 

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