The clathrin adaptor complex 1 directly binds to a sorting signal in Ste13p to reduce the rate of its trafficking to the late endosome of yeast.
Yeast trans-Golgi network (TGN) membrane proteins maintain steady-state localization by constantly cycling to and from endosomes. In this study, we examined the trafficking itinerary and molecular requirements for delivery of a model TGN protein A(F-->A)-alkaline phosphatase (ALP) to the prevacuolar/endosomal compartment (PVC). A(F-->A)-ALP was found to reach the PVC via early endosomes (EEs) with a half-time of approximately 60 min. Delivery of A(F-->A)-ALP to the PVC was not dependent on either the GGA or adaptor protein 1 (AP-1) type of clathrin adaptors, which are thought to function in TGN to PVC and TGN to EE transport, respectively. Surprisingly, in cells lacking the function of both GGA and AP-1 adaptors, A(F-->A)-ALP transport to the PVC was dramatically accelerated. A 12-residue cytosolic domain motif of A(F-->A)-ALP was found to mediate direct binding to AP-1 and was sufficient to slow TGN-->EE-->PVC trafficking. These results suggest a model in which this novel sorting signal targets A(F-->A)-ALP into clathrin/AP-1 vesicles at the EE for retrieval back to the TGN.
Foote
Christopher
C
Division of Biological Sciences, University of Missouri, Columbia, MO 65211, USA.
Nothwehr
Steven F
SF
D033961:Adaptor Protein Complex 1 / Q000378:metabolism*; D000469:Alkaline Phosphatase / Q000378:metabolism; D001665:Binding Sites / Q000502:physiology; D002451:Cell Compartmentation / Q000502:physiology; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000378:metabolism*; D015536:Down-Regulation / Q000502:physiology; D011992:Endosomes / Q000378:metabolism*; D008954:Models, Biological; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology*; D022161:Transport Vesicles / Q000378:metabolism; D014617:Vacuoles / Q000378:metabolism; D021601:trans-Golgi Network / Q000378:metabolism*
D033961:Adaptor Protein Complex 1; D029701:Saccharomyces cerevisiae Proteins; D000469:Alkaline Phosphatase; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C061833:STE13 protein, S cerevisiae