Schematic representation of the modular plant GH9 family structure. Specific domains comprise the cytosolic domain (white), transmembrane domain (wavy lines), signal sequence (dark grey), GH9 catalytic domain (light grey), linker region (thick black line), and carbohydrate binding module (dots). Structural subclasses are represented by SlGHl9A1/TomCel3 (class A, U78526), SlGH9B1/TomCel1 (class B, U13054), and SlGH9C1/TomCel8 (class C, AF098292).