The growing world of expansins

Plant Cell Physiol. 2002 Dec;43(12):1436-44. doi: 10.1093/pcp/pcf180.


Expansins are cell wall proteins that induce pH-dependent wall extension and stress relaxation in a characteristic and unique manner. Two families of expansins are known, named alpha- and beta-expansins, and they comprise large multigene families whose members show diverse organ-, tissue- and cell-specific expression patterns. Other genes that bear distant sequence similarity to expansins are also represented in the sequence databases, but their biological and biochemical functions have not yet been uncovered. Expansin appears to weaken glucan-glucan binding, but its detailed mechanism of action is not well established. The biological roles of expansins are diverse, but can be related to the action of expansins to loosen cell walls, for example during cell enlargement, fruit softening, pollen tube and root hair growth, and abscission. Expansin-like proteins have also been identified in bacteria and fungi, where they may aid microbial invasion of the plant body.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Review

MeSH terms

  • Amino Acid Sequence
  • Arabidopsis / drug effects
  • Arabidopsis / genetics
  • Arabidopsis / growth & development
  • Gene Expression Regulation, Developmental / drug effects
  • Gene Expression Regulation, Plant / drug effects
  • Indoleacetic Acids / pharmacology
  • Molecular Sequence Data
  • Plant Growth Regulators / genetics*
  • Plant Growth Regulators / metabolism
  • Plant Growth Regulators / pharmacology
  • Plant Growth Regulators / physiology
  • Plant Proteins / genetics*
  • Plant Proteins / metabolism
  • Plant Proteins / physiology


  • Indoleacetic Acids
  • Plant Growth Regulators
  • Plant Proteins
  • expansin protein, plant
  • indoleacetic acid