SORTING SIGNALS of PROTEIN TRAFFIC for the Nucleus,  Endomembranes, or Secretion 

SIGNAL

   Description

Destination

 Protein contains
Nuclear
Localizing
Signal 		  located anywhere in polypeptide;
  4 to 8 aa's, nucleoplasmin =
        [n-Pro-Lys-Lys-Lys-Arg-Lys-Val-c]		 cytoplasm
to  nucleus		 Nucleoplasmin: contains a
 Nuclear Localizing Signal
ER Signal
Sequence
   sequence of 6 to 30 amino acids
  near N-terminal; is mostly non-polar aa's		 into
E.R.  		ER Signal  &
ER Retention Signal
ER Retention
Signal		   sequence of 4 aa's, at c-terminal
            LYS-ASP-GLU-LEU-   		within
E.R.		 ER Signal &
ER Retention Signal
Golgi
Retention
Signal		   sequence of 20 hydrophobic non-polar aa's
   - forms transmembrane domain
     flanked by basic aa's		 into
Golgi		 ER Signal &
Golgi Retention Signal
Lysosome
Targeting 		  within polypeptide - basic charged aa's -
  leads to covalent links of mannose-6-P		 into Lysosome ER Signal &
Lysosomal Targeting Signal
Plasma Membrane   ER signal with stretch of non-polar
  hydrophobic transmembrane domain's
  that anchor it in membrane		 Plasma Membrane ER Signal &
hydrophobic domain aa's
Secretion  ER proteins encapsulated into vesicles Secretion ER Signal only               

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