Lysosomal membranes are enriched in extensively glycosylated transmembrane proteins, LAMP-1 and LAMP-2. LAMP-1 proteins have been characterized from several mammalian species and from chickens, but no non-mammalian homologues of LAMP-2 have been described, and no splice variants of either protein have been reported. Here we report the characterization of three cDNA clones encoding chicken LAMP-2. The nucleotide sequences of the cDNAs diverge at their 3′ ends within the open reading frame, resulting in sequences that code for three different transmembrane and cytoplasmic domains. Southern analysis suggests that a single gene encodes the common region of chicken LAMP-2. The position of the divergence and the identity of the common sequence are consistent with alternative splicing of 3′ exons. Analysis of the mRNAs present in adult chicken tissues suggests tissue-specific expression of the three chicken LAMP-2 variants, with LAMP-2b expressed primarily in the brain. The cytoplasmic domain of LAMP-type proteins contains the targeting signal for directing these molecules to the lysosome. Using chimeras consisting of the lumenal domain of chicken LEP100 (a LAMP-1) and the transmembrane and cytoplasmic domains of the LAMP-2 variants, we demonstrate in transfected mouse L cells that all three LAMP-2 carboxyl-terminal regions are capable of targeting the chimeric proteins to lysosomes. Levels of expression, subcellular distribution, and glycosylation of the LAMP proteins have all been shown to change with differentiation in mammalian cells and to be correlated with metastatic potential in certain tumor cell lines. Alternative splicing of the LAMP-2 transcript may play a role in these changes.

REFERENCES

Amos
B.
,
Lotan
R.
(
1990
).
Modulation of lysosomal-associated membrane glycoproteins during retinoic acid-induced embryonal carcinoma cell differentiation.
J. Biol. Chem
265
,
19192
19198
Anderson
M. J.
,
Fambrough
D. M.
(
1983
).
Aggregates of acetylcholine receptors are associated with plaques of a basal lamina heparin sulfate proteoglycan on the surface of skeletal muscle fibers.
J. Cell Biol
97
,
1396
1411
Arterburn
L. M.
,
Earles
B. J.
,
August
J. T.
(
1990
).
The disulfide structure of mouse lysosome-associated membrane protein 1.
J. Biol. Chem
265
,
7419
7423
Carlsson
S. R.
,
Fukuda
M.
(
1992
).
The lysosomal membrane glycoprotein lamp-1 is transported to lysosomes by two alternative pathways.
Arch. Biochem. Biophys
296
,
630
639
Cha
Y.
,
Holland
S. M.
,
August
J. T.
(
1990
).
The cDNA sequence of mouse LAMP-2.
J. Biol. Chem
265
,
5008
5013
Chen
J. W.
,
Murphy
T. L.
,
Willingham
M. C.
,
Pastan
I.
,
August
J. T.
(
1985
).
Identification of two lysosomal membrane glycoproteins.
J. Cell Biol
101
,
85
95
Chen
J. W.
,
Cha
Y.
,
Yuksel
K. U.
,
Gracy
R. W.
,
August
J. T.
(
1988
).
Isolation and sequencing of a cDNA clone encoding lysosomal membrane glycoprotein mouse LAMP-1.
J. Biol. Chem
263
,
8754
8758
Chirgwin
J. M.
,
Przybyla
R. J.
,
MacDonald
R. J.
,
Rutter
W. J.
(
1979
).
Isolation of active ribonucleic acid from sources enriched in ribonuclease.
Biochemistry
18
,
5294
5300
Fambrough
D. M.
,
Takeyasu
K.
,
Lippincott-Schwartz
J.
,
Siegel
N. R.
(
1988
).
Structure of LEP100, a glycoprotein that shuttles between lysosomes and the plasma membrane, deduced from the nucleotide sequence of the encoding cDNA.
J. Cell Biol
106
,
61
67
Fukuda
M.
,
Viitala
J.
,
Matteson
J.
,
Carlsson
S. R.
(
1988
).
Cloning of cDNAs encoding human lysosomal membrane glycoproteins, h-lamp-1 and h-lamp-2.
J. Biol. Chem
263
,
18920
18928
Fukuda
M.
(
1991
).
Lysosomal membrane glycoproteins.
J. Biol. Chem
266
,
21327
21330
Garrigues
J.
,
Anderson
J.
,
Hellstrom
K. E.
,
Hellstrom
I.
(
1994
).
Anti-tumor antibody BR96 blocks cell migration and binds to a lysosomalmembrane glycoprotein on cell surface microspikes and ruffled membranes.
J. Cell Biol
125
,
129
142
Granger
B. L.
,
Green
S. A.
,
Gabel
C. A.
,
Howe
C. L.
,
Mellman
I.
,
Helenius
A.
(
1990
).
Characterization and cloning of lgp110, a lysosomal membrane glycoprotein from mouse and rat cells.
J. Biol. Chem
265
,
12036
12043
Guarnieri
F. G.
,
Arterburn
L. M.
,
Penno
M. B.
,
Cha
Y.
,
August
J. T.
(
1993
).
The motif Tyr-X-X-hydrophobic residue mediates lysosomal membrane targeting of lysosome-associated membrane protein-1.
J. Biol. Chem
268
,
1941
1946
Hellstrom
I.
,
Garrigues
H. J.
,
Garrigues
U.
,
Hellstrom
K. E.
(
1990
).
Highly tumor-reactive, internalizing, mouse monoclonal antibodies to Ley-related cell surface antigens.
Cancer Res
50
,
2183
2190
Himeno
M.
,
Noguchi
Y.
,
Sasaki
H.
,
Tanaka
Y.
,
Furano
K.
,
Kono
A.
,
Sakaki
Y.
,
Kato
K.
(
1989
).
Isolation and sequencing of a cDNA clone encoding 107 kDa sialoglycoprotein in rat liver lysosomal membranes.
FEBS Lett
244
,
351
356
Ho
M.-K.
,
Springer
T. A.
(
1983
).
Tissue distribution, structural characterization and biosynthesis of Mac-3, a macrophage surface glycoprotein exhibiting molecular weight heterogeneity.
J. Biol. Chem
258
,
636
642
Howe
C. L.
,
Granger
B. L.
,
Hull
M.
,
Green
S. A.
,
Gabel
C. A.
,
Helenius
A.
,
Mellman
I.
(
1988
).
Derived protein sequence, oligosaccharides, and membrane insertion of the 120-kDa lysosomal membrane glycoprotein (lgp120): identification of a highly conserved family of lysosomal membrane glycoproteins.
Proc. Nat. Acad. Sci. USA
85
,
7577
7581
Hunziker
W.
,
Harter
C.
,
Matter
K.
,
Mellman
I.
(
1991
).
Basolateral sorting in MDCK cells requires a distinct cytoplasmic domain determinant.
Cell
66
,
907
920
Kornfeld
S.
,
Mellman
I.
(
1989
).
The biogenesis of lysosomes.
Annu. Rev. Cell Biol
5
,
483
525
Laferte
S.
,
Dennis
J. W.
(
1989
).
Purification of two glycoproteins expressing1-6 branched Asn-linked oligosaccharides from metastatic tumour cells.
Biochem. J
259
,
569
576
Lippincott-Schwartz
J.
,
Fambrough
D. M.
(
1986
).
Lysosomal membrane dynamics: structure and interorganellar movement of a major lysosomal membrane glycoprotein.
J. Cell Biol
102
,
1593
1605
Lippincott-Schwartz
J.
,
Fambrough
D. M.
(
1987
).
Cycling of the integral membrane glycoprotein, LEP100, between plasma membrane and lysosomes: kinetic and morphological analysis.
Cell
49
,
669
677
Mathews
P. M.
,
Martinie
J. B.
,
Fambrough
D. M.
(
1992
).
The pathway and targeting signal for delivery of the integral membrane glycoprotein LEP100 to lysosomes.
J. Cell Biol
118
,
1027
1040
Nabi
I. R.
,
Le Bivic
A.
,
Fambrough
D.
,
Rodriguez-Boulan
E.
(
1991
).
An endogenous MDCK lysosomal membrane glycoprotein is targeted basolaterally before delivery to lysosomes.
J. Cell Biol
115
,
1573
1584
Noguchi
Y.
,
Himeno
M.
,
Sasaki
H.
,
Tanaka
Y.
,
Kono
A.
,
Sakaki
Y.
,
Kato
K.
(
1989
).
Isolation and sequencing of a cDNA clone encoding 96 kDa sialoglycoprotein in rat liver lysosomal membranes.
Biochem. Biophys. Res. Commun
164
,
1113
1120
Saitoh
O.
,
Wang
W.-C.
,
Lotan
R.
,
Fukuda
M.
(
1992
).
Differential glycosylation and cell surface expression of lysosomal membrane glycoproteins in sublines of a human colon cancer exhibiting distinct metastatic potentials.
J. Biol. Chem
267
,
5700
5711
Sanger
F.
,
Nicklen
S.
,
Coulsen
A. R.
(
1977
).
DNA sequencing with chain-terminating inhibitors.
Proc. Nat. Acad. Sci. USA
74
,
5463
5467
Sawada
R.
,
Jardine
K. A.
,
Fukuda
M.
(
1993
).
The genes of major lysosomal membrane glycoproteins, Lamp-1 and Lamp-2.
J. Biol. Chem
268
,
9014
9022
Viitala
J.
,
Carlsson
S. R.
,
Siebert
P. D.
,
Fukuda
M.
(
1988
).
Molecular cloning of cDNAs encoding lamp A, a human lysosomal membrane glycoprotein with apparent Mr=120,000.
Proc. Nat. Acad. Sci. USA
85
,
3743
3747
Williams
M. A.
,
Fukuda
M.
(
1990
).
Accumulation of membrane glycoproteins in lysosomes requires a tyrosine residue at a particular position in the cytoplasmic tail.
J. Cell Biol
111
,
955
966
Zot
A. S.
,
Fambrough
D. M.
(
1990
).
Structure of a gene for a lysosomal membrane glycoprotein (LEP100).
J. Biol. Chem
265
,
20988
20995
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