Abstract
The protein product of the gene responsible for ocular albinism type 1, named OA1, is a pigment-cell-specific membrane glycoprotein, displaying features of G-protein-coupled receptors, yet exclusively localized to late endosomes, lysosomes and melanosomes. To dissect the signals responsible for the intracellular localization of OA1, we generated chimeric proteins consisting of the cytosolic domains of OA1 fused to the lumenal and transmembrane domains of LAMP1; in addition, we generated missense and deletion mutants of full-length OA1. Using this approach, we identified two separate sorting signals that are both necessary and sufficient for intracellular retention, as well as lysosomal and melanosomal localization, in melanocytic and non-melanocytic cells. These sorting signals are an unconventional dileucine motif within the third cytosolic loop and a novel motif, characterized by a tryptophan-glutamic acid doublet, within the C-terminal tail. Both motifs must be mutated to promote the plasma membrane localization of OA1, suggesting that they can independently drive its intracellular targeting. In addition, both motifs act similarly as lysosomal sorting signals in non-melanocytic cells, but appear to carry different specificities in melanocytic cells. Our findings indicate that OA1 contains multiple unconventional signals responsible for its lysosomal and melanosomal localization, and reveal a remarkable and unforeseen complexity in the regulation of polytopic protein sorting to specialized secretory organelles.
| Original language | English |
|---|---|
| Pages (from-to) | 2003-2014 |
| Number of pages | 12 |
| Journal | Journal of Cell Science |
| Volume | 119 |
| Issue number | 10 |
| DOIs | |
| Publication status | Published - May 15 2006 |
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Keywords
- GPCR
- Lysosome
- Melanosome
- Ocular albinism
- Sorting
ASJC Scopus subject areas
- Cell Biology
Cite this
An unconventional dileucine-based motif and a novel cytosolic motif are required for the lysosomal and melanosomal targeting of OA1. / Piccirillo, Rosanna; Palmisano, Ilaria; Innamorati, Giulio; Bagnato, Paola; Altimare, Domenico; Schiaffino, Maria Vittoria.
In: Journal of Cell Science, Vol. 119, No. 10, 15.05.2006, p. 2003-2014.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - An unconventional dileucine-based motif and a novel cytosolic motif are required for the lysosomal and melanosomal targeting of OA1
AU - Piccirillo, Rosanna
AU - Palmisano, Ilaria
AU - Innamorati, Giulio
AU - Bagnato, Paola
AU - Altimare, Domenico
AU - Schiaffino, Maria Vittoria
PY - 2006/5/15
Y1 - 2006/5/15
N2 - The protein product of the gene responsible for ocular albinism type 1, named OA1, is a pigment-cell-specific membrane glycoprotein, displaying features of G-protein-coupled receptors, yet exclusively localized to late endosomes, lysosomes and melanosomes. To dissect the signals responsible for the intracellular localization of OA1, we generated chimeric proteins consisting of the cytosolic domains of OA1 fused to the lumenal and transmembrane domains of LAMP1; in addition, we generated missense and deletion mutants of full-length OA1. Using this approach, we identified two separate sorting signals that are both necessary and sufficient for intracellular retention, as well as lysosomal and melanosomal localization, in melanocytic and non-melanocytic cells. These sorting signals are an unconventional dileucine motif within the third cytosolic loop and a novel motif, characterized by a tryptophan-glutamic acid doublet, within the C-terminal tail. Both motifs must be mutated to promote the plasma membrane localization of OA1, suggesting that they can independently drive its intracellular targeting. In addition, both motifs act similarly as lysosomal sorting signals in non-melanocytic cells, but appear to carry different specificities in melanocytic cells. Our findings indicate that OA1 contains multiple unconventional signals responsible for its lysosomal and melanosomal localization, and reveal a remarkable and unforeseen complexity in the regulation of polytopic protein sorting to specialized secretory organelles.
AB - The protein product of the gene responsible for ocular albinism type 1, named OA1, is a pigment-cell-specific membrane glycoprotein, displaying features of G-protein-coupled receptors, yet exclusively localized to late endosomes, lysosomes and melanosomes. To dissect the signals responsible for the intracellular localization of OA1, we generated chimeric proteins consisting of the cytosolic domains of OA1 fused to the lumenal and transmembrane domains of LAMP1; in addition, we generated missense and deletion mutants of full-length OA1. Using this approach, we identified two separate sorting signals that are both necessary and sufficient for intracellular retention, as well as lysosomal and melanosomal localization, in melanocytic and non-melanocytic cells. These sorting signals are an unconventional dileucine motif within the third cytosolic loop and a novel motif, characterized by a tryptophan-glutamic acid doublet, within the C-terminal tail. Both motifs must be mutated to promote the plasma membrane localization of OA1, suggesting that they can independently drive its intracellular targeting. In addition, both motifs act similarly as lysosomal sorting signals in non-melanocytic cells, but appear to carry different specificities in melanocytic cells. Our findings indicate that OA1 contains multiple unconventional signals responsible for its lysosomal and melanosomal localization, and reveal a remarkable and unforeseen complexity in the regulation of polytopic protein sorting to specialized secretory organelles.
KW - GPCR
KW - Lysosome
KW - Melanosome
KW - Ocular albinism
KW - Sorting
UR - http://www.scopus.com/inward/record.url?scp=33745193071&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=33745193071&partnerID=8YFLogxK
U2 - 10.1242/jcs.02930
DO - 10.1242/jcs.02930
M3 - Article
C2 - 16621890
AN - SCOPUS:33745193071
VL - 119
SP - 2003
EP - 2014
JO - Journal of Cell Science
JF - Journal of Cell Science
SN - 0021-9533
IS - 10
ER -