Expansin Genes
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This page describes the expansin gene family in Arabidopsis.  
For a detailed TABLE of Arabidopsis clones and corresponding expansin genes, click here.  
For a TABLE of expansin sequences and GenBank entries in other species, click here.
Click here for a sequence-based phylogenetic tree of Arabidopsis expansins. 

Alpha-expansins (designated EXPA):  
Arabidopsis contains 26 genes encoding for alpha-expansins, designated EXPA1-EXPA26. Most alpha-expansin genes have a conserved intron structure as indicated below. 

Intron lengths range from about 90 bp to 500 bp. Some alpha-expansin genes, e.g. EXPA17 - EXPA26, are missing intron #2. EXPA10 has an additional intron in the 5' untranslated region. 

Here is the sequence for intron #1 in EXP1 (highlighted in bright blue background):
      
+3   G  G  G   W  V  N  A   H  A  T   F  Y  G   G  G  D       protein seq.
 
    1763  CGGAGGAGGT TGGGTCAACG CACACGCCAC ATTCTACGGT GGTGGTGATG    nucleotide seq.
       +3 A  S  G  T   M  |
   
1813  CTTCCGGCAC AATGGGTATA TTTCCTTGAA CCTTCTCTCA CAAGTCACAA     INTRON I, PHASE=1
   
1863  GGCTTTAAAG CTTTCAARAT TTTTCCTTTA CCACAATTCT TATGAAATTT 

Here is the sequence for intron #2 in EXP1 (highlighted in bright blue background):
      
+2 F  D  L  S   Q  P  V   F  Q  R  I   A  Q  Y   R  A  G 
   
2163  TTGATCTCTC TCAGCCCGTA TTTCAACGCA TCGCTCAATA CAGAGCCGGC 
    2213  ATTGTCCCCG TCGCTTACCG AAGGTAAAAC CTAAAAAAAC ATAGCTGCTC     INTRON II, PHASE=2
   
2263  TGTTTTTACC TCAAAACAGA GTATGCGACT GAATAAAAAA TGAACATGAA    
   
2313  ACAGAGCTGC TCTGTTTTTC TTCCAAAACA GAGTATAGTG TATTATTGGA 
      
+1                                                | V  P 
   
2363  ATCTTACTCC GTTTTCAACT TTTTGTTGTT GTGTGTTTAA CAGAGTGCCG 

   
2413  TGCGTGAGAA GAGGAGGAAT AAGGTTTACG ATAAACGGAC ACTCTTACTT

 

Beta-expansins (designated EXPB): 

Arabidopsis has 5 complete beta-expansin genes, designated EXPB1-EXPB5. They typically contain three introns, two of which are conserved with alpha-expansins, and a third one that is not found in alpha-expansins and may be found before or after intron II. Below is the structure of EXPB1, in which the intron III is located after the intron II.

Expansin-like genes (designated EXLA and EXLB)

Arabidopsis has 4 genes that are related in sequence to alpha and beta-expansins. Three of these make up a distinct group in phylogenetic sequence analysis, and are designed EXLA1-EXLA3. A fourth gene that also has sequence relatedness to expansins falls outside the EXPL group, and it has been designated EXLB1. 

horizontal rule

Naming conventions:  The gene symbol  is "EXPA" for alpha-expansin and "EXPB" for beta-expansin. This abbreviation is followed by a number which is assigned serially in order of discovery and may be preceded by two or five letters designating the genus & species, e.g. Cs-EXPA1, Cs-EXPA2, At-EXPA1, At-EXPA2 for the first two alpha-expansins discovered in Cucumis sativus (cucumber) and Arabidopsis thaliana, respectively; At-EXPB1, ZmEXPB2 are the designations for beta-expansin1 from Arabidopsis and beta-expansin2 from Zea mays, respectively.  The five-letter species designation recommended by the ISPMB Commission on Plant Gene Nomenclature would have these genes designated as CUCsa;EXPA1, CUCsa;EXPA2, ARAth;EXPA1, ARAth;EXPA2, and so on.

For more details, see Nomenclature.

If you want to assign a number to an expansin that you discovered, please check that the number has not already been used by contacting Daniel Cosgrove. I'll be glad to coordinate among groups to prevent naming conflicts.
 

This page was last updated on 03/22/06.

Send Comments to mailto:dcosgrove@psu.edu