Modified RING finger, HC subclass (C4C4-type), found in Arabidopsis thaliana cellulose synthase A (CesA) catalytic subunits 1-10, and similar proteins from plants
This subfamily includes plant catalytic subunits of cellulose synthase terminal complexes ("rosettes") required for beta-1,4-glucan microfibril crystallization, a major mechanism of cell wall formation. CesA1, also known as protein RADIALLY SWOLLEN 1 (RSW1), is required during embryogenesis for cell elongation, orientation of cell expansion and complex cell wall formations, such as interdigitated pattern of epidermal pavement cells, stomatal guard cells, and trichomes. It plays a role in lateral roots formation, but seems unnecessary for the development of tip-growing cells such as root hairs. CesA2, also known as Ath-A, is involved in the primary cell wall formation. It forms a homodimer. CesA3, also known as constitutive expression of VSP1 protein 1, isoxaben-resistant protein 1, Ath-B, protein ECTOPIC LIGNIN 1, or protein RADIALLY SWOLLEN 5 (RSW5), is involved in primary cell wall formation, especially in roots. CesA4, also known as protein IRREGULAR XYLEM 5 (IRX5), is involved in the secondary cell wall formation, and required for xylem cell wall thickening. CesA5 may be partially redundant with CesA6. CesA6, also known as AraxCelA, isoxaben-resistant protein 2, protein PROCUSTE 1, or protein QUILL, is involved in primary cell wall formation. Like CesA1, CesA6 is critical for cell expansion. CESA6-dependent cell elongation seems to be independent of gibberellic acid, auxin, and ethylene. CesA6 interacts with and moves along cortical microtubules for the process of cellulose deposition. CesA7, also known as protein FRAGILE FIBER 5, or protein IRREGULAR XYLEM 3 (IRX3), and CesA8, also known as protein IRREGULAR XYLEM 1 (IRX1) or protein LEAF WILTING 2, are both involved in secondary cell wall formation and also required for xylem cell wall thickening. The biological function of CesA9 and CesA10 remain unclear. CesA1, CesA3, and CesA6 form a functional complex essential for primary cell wall cellulose synthesis, while CesA4, CesA7, and CesA8 form a functional complex located in secondary cell wall deposition sites. All family members contain an N-terminal C4C4-type RING-HC finger and a C-terminal glycosyltransferase family A (GT-A) domain.
Comment:consensus of the typical C3HC4-type RING-HC finger: C-X2-C-X(9-39)-C-X(1-3)-H-X(2-3)-C-X2-C-X(4-48)-C-X2-C, X is any amino acid and the number of X residues varies in different fingers.
Comment:A RING finger typically binds two zinc atoms, with its Cys and/or His side chains in a unique "cross-brace" arrangement.
Jiyao W et al.(2023). "The conserved domain database in 2023.",