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PR00788

Identifier
NITROPHORIN  [View Relations]  [View Alignment]  
Accession
PR00788
No. of Motifs
6
Creation Date
01-SEP-1997  (UPDATE 23-AUG-1999)
Title
Nitrophorin signature
Database References
PRINTS; PR00179 LIPOCALIN
INTERPRO; IPR002351
PDB; 1NP1; 2NP1; 3NP1; 4NP1
SCOP; 1NP1; 2NP1; 3NP1
CATH; 1NP1; 2NP1; 3NP1
Literature References
1. PERVAIS, S. AND BREW, K. 
Homology of beta-lactoglobulin, serum retinol-binding protein and 
protein HC.
SCIENCE 228 335-337 (1985).
 
2. FLOWER D.R.
The Lipocalin protein family: structure and function.
BIOCHEM.J. 318 1-14 (1996).
 
3. FLOWER, D.R., NORTH, A.C.T. AND ATTWOOD, T.K.
Structural and sequence relationships in the lipocalins and related
proteins.
PROTEIN SCI. 2 753-761 (1993). 
 
4. FLOWER, D.R.
Multiple molecular recognition properties of the lipocalin protein family.
J.MOL.REC. 8 185-195 (1995).
 
5. WEISCHEL, A, ANDERSEN, J.F., CHAMPAGNE, D.E., Walker, F.A. AND 
MONTFORT, W.R.
Crystal structure of a nitric oxide transport protein from a blood-sucking
insect.
NAT.STRUCT.BIOL. 5 304-309 (1998).
 
6. ANDERSEN, J.F., WEISCHEL, A, BALFOUR, C.A., CHAMPAGNE, D.E., AND 
MONTFORT, W.R.
The crystal structure of nitrophorin 2 at 1.5 angstroms resolution:
transport of nitric oxide by a lipocalin-based heme protein.
STRUCTURE 6 1315-1327 (1998).

Documentation
The lipocalins are a diverse, interesting, yet poorly understood family of 
proteins composed, in the main, of extracellular ligand-binding proteins
displaying high specificity for small hydrophobic molecules [1,2]. Functions
of these proteins include transport of nutrients, control of cell regula-
tion, pheromone transport, cryptic colouration, and the enzymatic synthesis
of prostaglandins.
   
The crystal structures of several lipocalins have been solved and show a 
novel 8-stranded anti-parallel beta-barrel fold well conserved within the
family. Sequence similarity within the family is at a much lower level and
would seem to be restricted to conserved disulphides and 3 motifs, which
form a juxtaposed cluster that may act as a common cell surface receptor
site [2]. By contrast, at the more variable end of the fold are found an 
internal ligand binding site and a putative surface for the formation of 
macromolecular complexes [4]. The anti-parallel beta-barrel fold is also
exploited by the fatty acid-binding proteins (which function similarly by
binding small hydrophobic molecules), by avidin and the closely related
metalloprotease inhibitors, and by triabin. Similarity at the sequence 
level, however, is less obvious, being confined to a single short 
N-terminal motif.
 
The lipocalin family can be subdivided into kernal and outlier sets. The 
kernal lipocalins form the largest self-consistent group (see LIPOCALIN
signature). The outlier lipocalins form several smaller distinct subgroups: 
the OBPs, the von Ebner's gland proteins, alpha-1-acid glycoproteins, tick
histamine binding proteins and the nitrophorins.
    
The nitrophorins [5,6] are a recently identified group of lipocalin outliers
that bind nitric oxide. They are present in the saliva of blood sucking 
insects, where they function as vasodilators and anticoagulent agents. 
    
NITROPHORIN is a 6-element fingerprint that provides a signature for the 
nitrophorins. The fingerprint was derived from an initial alignment of 2
sequences: the motifs were drawn from short conserved regions spanning
virtually the full alignment length - motif 1 includes part of the GxW 
triplet, which resides in the first beta-strand (cf. LIPOCALIN signature
motif 1 and PROSITE pattern LIPOCALIN (PS00213)); motif 2 contains the haem 
attachment site; motif 3 encodes strand 4; motif 4 spans strands 7 and 8
(cf. LIPOCALIN signature motif 2); motif 5 encodes strand 9; and motif 6
spans helices 2 and 3. Two iterations on SPRT37_10f were required to reach
convergence, at which point a true set comprising 5 sequences was identified.
Summary Information
5 codes involving  6 elements
0 codes involving 5 elements
0 codes involving 4 elements
0 codes involving 3 elements
0 codes involving 2 elements
Composite Feature Index
6555555
5000000
4000000
3000000
2000000
123456
True Positives
NP1_RHOPR     NP2_RHOPR     NP3_RHOPR     NP4_RHOPR     
O77000
Sequence Titles
NP1_RHOPR   NITROPHORIN 1 PRECURSOR (NP1) - RHODNIUS PROLIXUS. 
NP2_RHOPR NITROPHORIN 2 PRECURSOR (NP2) (PROLIXIN-S) - RHODNIUS PROLIXUS.
NP3_RHOPR NITROPHORIN 3 PRECURSOR (NP3) - RHODNIUS PROLIXUS.
NP4_RHOPR NITROPHORIN 4 PRECURSOR (NP4) - RHODNIUS PROLIXUS.
O77000 NITROPHORIN-3 - RHODNIUS PROLIXUS.
Scan History
SPTR37_10f 2  100  NSINGLE    
Initial Motifs
Motif 1  width=12
Element Seqn Id St Int Rpt
TWYVTHYLDKDP NP3_RHOPR 44 44 -
VWYVTDYLDLEP NP4_RHOPR 43 43 -

Motif 2 width=13
Element Seqn Id St Int Rpt
GTVKEALYHFNSK NP3_RHOPR 72 16 -
GKLKEALYHYDPK NP4_RHOPR 72 17 -

Motif 3 width=14
Element Seqn Id St Int Rpt
SFYNIGEGKLGSSG NP3_RHOPR 88 3 -
TFYDVSELQVESLG NP4_RHOPR 88 3 -

Motif 4 width=20
Element Seqn Id St Int Rpt
YTLTVLEADDSSALVHICLR NP3_RHOPR 127 25 -
YTFTVMYADDSSALIHTCLH NP4_RHOPR 126 24 -

Motif 5 width=14
Element Seqn Id St Int Rpt
KDLGDLYTVLSHQK NP3_RHOPR 150 3 -
KDLGDLYAVLNRNK NP4_RHOPR 149 3 -

Motif 6 width=16
Element Seqn Id St Int Rpt
VKNAVAQAGLKLNDFV NP3_RHOPR 171 7 -
VKSAVSAATLEFSKFI NP4_RHOPR 170 7 -
Final Motifs
Motif 1  width=12
Element Seqn Id St Int Rpt
TWYVTHYLDKDP NP3_RHOPR 44 44 -
TWYVTHYLDKDP O77000 44 44 -
KWYVTHFLDKDP NP2_RHOPR 44 44 -
VWYVTDYLDLEP NP1_RHOPR 45 45 -
VWYVTDYLDLEP NP4_RHOPR 43 43 -

Motif 2 width=13
Element Seqn Id St Int Rpt
GTVKEALYHFNSK NP3_RHOPR 72 16 -
GTVKEALYHFNSK O77000 72 16 -
GTVKEALYHYNAN NP2_RHOPR 72 16 -
GKLKEALYHYDPK NP1_RHOPR 74 17 -
GKLKEALYHYDPK NP4_RHOPR 72 17 -

Motif 3 width=14
Element Seqn Id St Int Rpt
SFYNIGEGKLGSSG NP3_RHOPR 88 3 -
SFYNIGEGKLGSAG O77000 88 3 -
SFYNIGEGKLESSG NP2_RHOPR 88 3 -
TFYDVSELQEESPG NP1_RHOPR 90 3 -
TFYDVSELQVESLG NP4_RHOPR 88 3 -

Motif 4 width=20
Element Seqn Id St Int Rpt
YTLTVLEADDSSALVHICLR NP3_RHOPR 127 25 -
YTLTVLEADDSSALVHICLR O77000 127 25 -
YTLTVLEADDSSALVHICLR NP2_RHOPR 127 25 -
YTFTVMYADDSSALIHTCLH NP1_RHOPR 128 24 -
YTFTVMYADDSSALIHTCLH NP4_RHOPR 126 24 -

Motif 5 width=14
Element Seqn Id St Int Rpt
KDLGDLYTVLSHQK NP3_RHOPR 150 3 -
KDLGDLYTVLSHQK O77000 150 3 -
KDLGDLYTVLTHQK NP2_RHOPR 150 3 -
KDLGDLYAVLNRNK NP1_RHOPR 151 3 -
KDLGDLYAVLNRNK NP4_RHOPR 149 3 -

Motif 6 width=16
Element Seqn Id St Int Rpt
VKNAVAQAGLKLNDFV NP3_RHOPR 171 7 -
VKNAVAQAGLKLNDFV O77000 171 7 -
VKSAVTQAGLQLSQFV NP2_RHOPR 171 7 -
VKGAVTAASLKFSDFI NP1_RHOPR 172 7 -
VKSAVSAATLEFSKFI NP4_RHOPR 170 7 -