| Primary Identifier | IPR044630 | Type | Family |
| Short Name | SPA1/2/3/4 |
| description | In Arabidopsis, SPA1/2/3/4 play a central role in suppression of photomorphogenesis. SPA1 and SPA2 predominate in dark-grown seedlings, whereas SPA3 and SPA4 prevalently regulate the elongation growth in adult plants []. SPAs contain a kinase-like domain, a coiled-coil domain and the WD-repeats. SPAs and COP1 (a ring finger E3 ubiquitin ligase) can form homo- and heterodimers via their respective coiled-coil domains, and the COP1/SPA complex forms a tetramer of two COP1 and two SPA proteins []. The SPA proteins can self-associate or interact with each other, forming a heterogeneous group of SPA-COP1 complexes []. Besides recognizing substrates, both COP1 and SPA bind DDB1 in the CUL4 complex through their C-terminal WD-repeat domains. They serve as DDB1-CUL4-associated factors (DCAFs) similar to other substrate adaptors in CUL4-based E3 ligases. SPA1 interacts with photoreceptor cry2 via its kinase-like domain, with cry1 via its WD-repeat domain and with phytochromes possibly via both []. SPAs have also been shown to regulate the phyB-PIF4 module at high ambient temperature []. |
