An acidic sequence within the cytoplasmic domain of furin functions as a determinant of trans-Golgi network localization and internalization from the cell surface.
The mammalian endopeptidase, furin, is predominantly localized to the trans-Golgi network (TGN) at steady state. The localization of furin to this compartment seems to be the result of a dynamic process in which the protein undergoes cycling between the TGN and the plasma membrane. Both TGN localization and internalization from the plasma membrane are mediated by targeting information contained within the cytoplasmic domain of furin. Here, we report the results of a mutagenesis analysis aimed at identifying the source(s) of targeting information within the furin cytoplasmic domain. Our studies show that there are at least two cytoplasmic determinants that contribute to the steady-state localization and trafficking of furin. The first determinant corresponds to a canonical tyrosine-based motif, YKGL (residues 758-761), that functions mainly as an internalization signal. The second determinant consists of a strongly hydrophilic sequence (residues 766-783) that contains a large cluster of acidic residues (E and D) and is devoid of any tyrosine-based or di-leucine-based motifs. This second determinant is capable of conferring localization to the TGN as well as mediating internalization from the plasma membrane. Thus, these observations establish the existence of a novel, autonomous determinant distinct from sorting signals described previously.
Voorhees
P
P
Cell Biology and Metabolism Branch, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA.
Deignan
E
E
van Donselaar
E
E
Humphrey
J
J
Marks
M S
MS
Peters
P J
PJ
Bonifacino
J S
JS
D000595:Amino Acid Sequence; D000600:Amino Acids, Dicarboxylic; D000941:Antigens / Q000235:genetics; D002451:Cell Compartmentation; D002462:Cell Membrane / Q000201:enzymology* / Q000648:ultrastructure; D004705:Endocytosis; D005434:Flow Cytometry; D005455:Fluorescent Antibody Technique; D045683:Furin; D006056:Golgi Apparatus / Q000201:enzymology* / Q000648:ultrastructure; D006367:HeLa Cells; D006801:Humans; D008969:Molecular Sequence Data; D011233:Precipitin Tests; D015375:Receptors, Interleukin-2 / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D017384:Sequence Deletion; D013329:Structure-Activity Relationship; D013381:Subtilisins / Q000302:isolation & purification / Q000378:metabolism*; D014443:Tyrosine
D000600:Amino Acids, Dicarboxylic; D000941:Antigens; D015375:Receptors, Interleukin-2; D011993:Recombinant Fusion Proteins; D014443:Tyrosine; D013381:Subtilisins; D045683:Furin