Sequence-dependent sorting of recycling proteins by actin-stabilized endosomal microdomains.
The functional consequences of signaling receptor endocytosis are determined by the endosomal sorting of receptors between degradation and recycling pathways. How receptors recycle efficiently, in a sequence-dependent manner that is distinct from bulk membrane recycling, is not known. Here, in live cells, we visualize the sorting of a prototypical sequence-dependent recycling receptor, the beta-2 adrenergic receptor, from bulk recycling proteins and the degrading delta-opioid receptor. Our results reveal a remarkable diversity in recycling routes at the level of individual endosomes, and indicate that sequence-dependent recycling is an active process mediated by distinct endosomal subdomains distinct from those mediating bulk recycling. We identify a specialized subset of tubular microdomains on endosomes, stabilized by a highly localized but dynamic actin machinery, that mediate this sorting, and provide evidence that these actin-stabilized domains provide the physical basis for a two-step kinetic and affinity-based model for protein sorting into the sequence-dependent recycling pathway.
Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, PA, USA. map3@andrew.cmu.edu
Manojkumar A
MA
Puthenveedu
Benjamin
B
Lauffer
Paul
P
Temkin
Rachel
R
Vistein
Peter
P
Carlton
Kurt
K
Thorn
Jack
J
Taunton
Orion D
OD
Weiner
Robert G
RG
Parton
Mark
M
von Zastrow
D000199:Actins / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D003599:Cytoskeleton / Q000378:metabolism; D011992:Endosomes / Q000378:metabolism*; D006801:Humans; D007700:Kinetics; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D018343:Receptors, Adrenergic, beta-2 / Q000737:chemistry / Q000378:metabolism; D017465:Receptors, Opioid, delta / Q000378:metabolism
D000199:Actins; D018343:Receptors, Adrenergic, beta-2; D017465:Receptors, Opioid, delta