The AP-3-dependent targeting of the melanosomal glycoprotein QNR-71 requires a di-leucine-based sorting signal.
J Cell Sci
; 114(Pt 15): 2831-41, 2001 Aug.
Article
in En
| MEDLINE
| ID: mdl-11683416
ABSTRACT
The Quail Neuroretina clone 71 gene (QNR-71) is expressed during the differentiation of retinal pigmented epithelia and the epidermis. It encodes a type I transmembrane glycoprotein that shares significant sequence homologies with several melanosomal proteins. We have studied its intracellular traffic in both pigmented and non-pigmented cells. We report that a di-leucine-based sorting signal (ExxPLL) present in the cytoplasmic domain of QNR-71 is necessary and sufficient for its proper targeting to the endosomal/premelanosomal compartments of both pigmented and non-pigmented cells. The intracellular transport of QNR-71 to these compartments is mediated by the AP-3 assembly proteins. As previously observed for the lysosomal glycoproteins Lampl and LimpII, overexpression of QNR-71 increases the amount of AP-3 associated with membranes, and inhibition of AP-3 synthesis increases the routing of QNR-71 towards the cell surface. In addition, expression of QNR-71 induces a misrouting of endogenous LampI to the cell surface. Thus, the targeting of QNR-71 might be similar to that of the lysosomal integral membrane glycoproteins LampI and LimpII. This suggests that sorting to melanosomes and lysosomes requires similar sorting signals and transport machineries.
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Collection:
01-internacional
Database:
MEDLINE
Main subject:
Pigment Epithelium of Eye
/
Protein Sorting Signals
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Carrier Proteins
/
Melanosomes
/
Monomeric Clathrin Assembly Proteins
/
Eye Proteins
/
Membrane Proteins
Limits:
Animals
/
Humans
Language:
En
Journal:
J Cell Sci
Year:
2001
Document type:
Article
Affiliation country:
France