Home About Expansins... Protein Structure Expansin Genes abstracts Nomenclature

An ad hoc working group for expansin nomenclature reached concensus on a revision of expansin names and symbols in April 2004. Their recommendations were published in Plant Molecular Biology 55:311-314 and are briefly summarized as follows:

Only two-domain proteins will be designated as members of the expansin superfamily. The name "expansin" should not given to proteins that are homologous to only one of the expansin domains, i.e. the GH45-like domain I (SCOP 1.63 50685) and the grass pollen group-2 allergen-like domain II (SCOP 1.63 49590). The terms "g-expansin" and "d-expansin" should be abandoned. 

To determine which family a gene belongs to, click here.

Accepted symbols for plant genes:

bulleta-expansin (formerly EXP) becomes EXPA
bulletb-expansin (formerly EXPB) remains EXPB
bulletExpansin like (formerly EXPL) becomes EXLA (for expansin-like family A)
bulletExpansin related (formerly EXPR) becomes EXLB (for expansin-like family B)
bulletIf any new gene families within this superfamily are discovered in plants, they will be given symbols EXLC, EXLD, after consultation with the working group.
bulletThe symbol EXLX (Expansin-like Group X) may be used to designate genes that fulfill these criteria:
bulletthey are from organisms outside the plant world,
bulletthey are homologous to expansins (that is, with homology to both domains)
bulletthey do not fall within the established families
bulletEXLX should not be interpreted to indicate a true (monophyletic) family, but rather it is a polyphyletic group, a catch-all group for expansin related sequences that do not fall into the recognized families.

horizontal rule

Table 1.  Revised names and symbols of expansin genes. ___________________________________________________________________________


Original name                     Former symbola                       New symbol    New name



á-Expansin                           EXP or EXPá1                        EXPA               EXPANSIN A

â-Expansin                           EXPB or EXPâ1                      EXPB              EXPANSIN B

Expansin-like                       EXPL or EXPâ2                      EXLA               EXPANSIN-LIKE A

Expansin-related                  EXPR or EXPâ3                      EXLB               EXPANSIN-LIKE B

Various                                 EXP or none                            EXLX               EXPANSIN-LIKE X


Numbering should be in order of discovery, e.g. EXPA1, EXPA2, ...

Upper case, italicized symbols are used for gene names
Upper case, not italicized, symbols are used for proteins
Lower case, italicized symbols are used for mutant genes


horizontal rule

The expansin working group consists of:

Hans Kende1,*, Kent J. Bradford2, David A. Brummell3, Hyung-Taeg Cho4, Daniel J. Cosgrove5, Andrew J. Fleming6, Chris Gehring7, Yi Lee8, Simon McQueen-Mason9, Jocelyn K.C. Rose10 L.A.C.J. Voesenek11

1MSU-DOE Plant Research Laboratory, Michigan State University, East Lansing, MI 48824, USA (*author for correspondence; e-mail; 2Seed Biotechnology Center, University of California, Davis CA 95616, USA; 3Crop and Food Research, Private Bag 11600, Palmerston North, 5301, New Zealand; 4School of Biosciences and Biotechnology, Chungnam National University, Daejeon 305-764, Republic of Korea; 5Department of Biology, 208 Mueller Laboratory, Pennsylvania State University, University Park, PA 16802, USA; 6Department of Animal and Plant Sciences, University of Sheffield, Western Bank, Sheffield S10 2TN, UK; 7University of the Western Cape, Department of Biotechnology, Private Bag X17, Bellville 7535, South Africa; 8Department of Tobacco Science, Chungbuk National University, 48 Gaesin-dong Hungduk-ku, Chongju 361-763, Republic of Korea; 9Biology Department, University of York, PO Box 373, York, YO10 5YW, UK; 10Department of Plant Biology, Cornell University, Ithaca, NY 14853, USA; 11Plant Ecophysiology, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands




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

Send Comments to