InterPro domain: IPR039613

This entry represents a group of plant proteins, including SPR1 and SP1L1-5 from Arabidopsis. They may share the same functions and act redundantly to control directional cell expansion by organizing cortical microtubule orientation [ 1 ].

Arabidopsis spiral1 (spr1) mutants were isolated based on their characteristic rightward slanting root growth on vertically oriented agar plates [ 2 ]. SPR1 has been found to interact with EB1b and microtubule to regulate microtubule dynamic instability [ 3 ]. Upon salt stress, 26S proteasome-dependent degradation of SPR1 facilitates the microtubule depolymerization needed for the survival of plant cells [ 4 ].

1. Salt stress-induced disassembly of Arabidopsis cortical microtubule arrays involves 26S proteasome-dependent degradation of SPIRAL1. Plant Cell 23, 3412-27
2. The SPIRAL genes are required for directional control of cell elongation in Aarabidopsis thaliana. Development 127, 4443-53
3. The microtubule plus-end tracking proteins SPR1 and EB1b interact to maintain polar cell elongation and directional organ growth in Arabidopsis. Plant Cell 26, 4409-25