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PR01381

Identifier
CLAUDIN7  [View Relations]  [View Alignment]  
Accession
PR01381
No. of Motifs
3
Creation Date
27-JUL-2000
Title
Claudin-7 signature
Database References
PRINTS; PR01077 CLAUDIN
Literature References
1. TSUKITA, S. AND FURUSE, M.
Occuldin and claudins in tight-junction strands: leading or supporting
players?
TRENDS CELL BIOL. 9 268-273 (1999).
 
2. FURUSE, M., FUJITA, K., HIIRAGI, T., FUJIMOTO, K. AND TSUKITA, S.
Claudin-1 and -2: novel integral membrane proteins localizing at tight 
junctions with no sequence similarity to occludin.
J.CELL BIOL. 141 1539-1550 (1998).
 
3.FURUSE, M., SASAKI, H., FUJIMOTO, K. AND TSUKITA, S.
A single gene product, claudin-1 or -2, reconstitutes tight junction 
strands and recruits occludin in fibroblasts.
J.CELL BIOL. 143 391-401 (1998).
 
4. MORITA, K., FURUSE, M., FUJIMOTO, K. AND TSUKITA, S.
Claudin multigene family encoding four-transmembrane domain protein
components of tight junction strands.
PROC.NATL.ACAD.SCI.U.S.A. 96 511-516 (1999).

Documentation
PRINTS; PR01379 CLAUDIN4; PR01380 CLAUDIN5; PR01382 CLAUDIN9
Tight junctions (TJs) are specialised membrane domains found at the most 
apical region of polarised epithelial and endothelial cells. They create a 
primary barrier, preventing paracellular transport of solutes and 
restricting lateral diffusion of membrane lipids and proteins. They also 
act as diffusion barriers within plasma membranes, creating and maintaining
apical and basolateral membrane domains.
 
Recently, the molecular architecture of tight junctions has begun to be
elucidated. One group of proteins thought to be major components of TJs 
is the claudin family [1]. Immunofluorescence studies have shown that 
claudins are targeted to and incorporated into tight junctions [2]. 
Furthermore, when claudins are introduced into cells that lack tight 
junctions, networks of strands and grooves form at cell-cell contact sites 
that closely resemble native TJs [3].
 
The claudin protein family is encoded by at least 17 human genes, with many
homologues cloned from other species. Tissue distribution patterns for the 
claudin family members are distinct. Claudin-1 and -2, for example, are 
expressed at high levels in the liver and kidney, whereas claudin-3 mRNA is
detected mainly in the lung and liver [2,4]. This suggests that multiple 
claudin family members may be involved in tight junction strand formation 
in a tissue-dependent manner.
 
Hydropathy analysis suggests that all claudins share a common transmembrane
(TM) topology. Each family member is predicted to possess four TM domains 
with intracellular N- and C-termini. Although their C-terminal cytoplasmic 
domain sequences vary, most claudin family members share a common motif of 
-Y-V in this region. This has been postulated as a possible binding motif 
for PDZ domains of other tight junction-associated membrane proteins, such 
as ZO-1.
 
Claudin-7 was identified through searching expressed sequence tag (EST)
databases for sequences similar to claudin-1 and -2 [4]. It was 
subsequently cloned and expressed in cells, where it was shown to
concentrate at tight junctions [4].
 
CLAUDIN7 is a 3-element fingerprint that provides a signature for claudin-7
proteins. The fingerprint was derived from an initial alignment of 2 
sequences: the motifs were drawn from conserved regions spanning virtually 
the full alignment length, focusing on those sections that characterise
claudin-7 and distinguish it from other family members - motif 1 lies in
the first TM domain; motif 2 resides within in the intracellular loop; and 
motif 3 lies in the cytoplasmic C-terminal region. A single iteration on 
SPTR37_10f was required to reach convergence, no further sequences being 
identified beyond the starting set. Note that O95471, annotated in TrEMBL
as claudin-9, has recently been reclassified as Homo sapiens claudin-7.
Summary Information
2 codes involving  3 elements
0 codes involving 2 elements
Composite Feature Index
3222
2000
123
True Positives
O95471        Q9Z261        
Sequence Titles
O95471      CLAUDIN-9 - HOMO SAPIENS (HUMAN).             
Q9Z261 CLAUDIN-7 - MUS MUSCULUS (MOUSE).
Scan History
SPTR37_10f 1  300  NSINGLE    
Initial Motifs
Motif 1  width=7
Element Seqn Id St Int Rpt
GFSMALL O95471 10 10 -
GFSMAML Q9Z261 10 10 -

Motif 2 width=10
Element Seqn Id St Int Rpt
CGGDDKVKKA O95471 107 90 -
CGGDDKAKKA Q9Z261 107 90 -

Motif 3 width=12
Element Seqn Id St Int Rpt
RAPRSYPKSNSS O95471 196 79 -
RAPRSYPKSNSS Q9Z261 196 79 -
Final Motifs
Motif 1  width=7
Element Seqn Id St Int Rpt
GFSMALL O95471 10 10 -
GFSMAML Q9Z261 10 10 -

Motif 2 width=10
Element Seqn Id St Int Rpt
CGGDDKVKKA O95471 107 90 -
CGGDDKAKKA Q9Z261 107 90 -

Motif 3 width=12
Element Seqn Id St Int Rpt
RAPRSYPKSNSS O95471 196 79 -
RAPRSYPKSNSS Q9Z261 196 79 -