PR-2 Family Members (ß-1,3-Glucanases) of Tobacco and Other Nicotiana Species

Class (a) Member name Trivial name Origin (b) MW (kDa) (c) pI Localization
I PR-2e Glb Nt (T) 33 Basic Vacuole
I PR-2e Gla Nt (S) 33 Basic Vacuole
I PR-2e Gglb50 Nt (S) Basic Vacuole
I PR-2e Gln2 Nt (S) Basic Vacuole
I Gn2 (d) Np Basic Vacuole
I Gn1 (d) Np 34 Basic Vacuole
I I PR-2a PR-2 (I, b4) Nt 35 Acidic Secreted
I I PR-2b PR-N (b5), G19 Nt 35 Acidic Secreted
I I PR-2c PR-O (b6(b), O') Nt 35 Acidic Secreted
I I PR-2d Nt Acidic Secreted
I I Stylar ßGLU (e) Sp41a Nt 41 Acidic Secreted
I I Stylar ßGLU (e) Sp41b Nt 41 Acidic Secreted
I I I PR-2d PR-Q' Nt 35 Acidic Secreted
I V (f) anther ßGLU (e) Tag1 Nt 35 Acidic Secreted

Table 3.1: © Review "Functions and Regulation of Plant ß-1,3-Glucanases (PR-2)" by Leubner-Metzger and Meins (1999).
(a) Classification according to amino acid sequence identity of the mature proteins.
(b) Nicotiana tabacum (Nt); N. plumbaginifolia (Np); T and S refer to the N. tometosiformis and N. sylvestris progenitors of tobacco, respectively.
(c) Approximate molecular weight of mature protein; Selected values from the literature, which might differ between publications.
(d) Amino acid sequence identity to tobacco ßGLU I enzymes of the N. plumbaginifolia enzymes is ca. 98 % for Gn2, but only ca. 76 % for Gn1.
(e) Not induced by pathogens, i.e. a "PR-like protein".
(f) Tag1 is assigned to a new class, since it shares only 37-38 % amino sequence identity to Gla, PR-2, and PR-Q'.


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