Protein: Guanine nucleotide exchange factor SPIKE 1 (Q8SAB7)
Organism: Arabidopsis thaliana (Mouse-ear cress)
Function: Guanine nucleotide exchange factor (GEF) for Rho and Rac. GEF proteins activate small GTPases by exchanging bound GDP for free GTP. Controls actin polymerization via the two heteromeric complexes WAVE and actin-related protein (ARP) 2/3. Involved in cytoskeletal reorganization required for cell shape (e.g. trichome and cotyledon) control and tissue development. Promotes polarized growth and cell-cell adhesion in the leaf epidermis probably by promoting the formation of endoplasmic reticulum (ER) exit site (ERES) and/or trafficking between the ER and Golgi. Triggers ARAC3/ROP6 activation required for auxin-mediated inhibition of PIN2 internalization during gravitropic responses.
Subcellular location: Cytoplasm {ECO:0000250|UniProtKB:B2RY04}. Endoplasmic reticulum membrane; Peripheral membrane protein {ECO:0000269|PubMed:21109438}. Nucleus {ECO:0000269|PubMed:21109438}. Note=Accumulates at, and promotes the formation of, a specialized domain of the endoplasmic reticulum termed the ER exit site (ERES). {ECO:0000269|PubMed:21109438}.
Interaction partners:
- Rac-like GTP-binding protein ARAC4
- Rac-like GTP-binding protein ARAC3
- Rac-like GTP-binding protein ARAC5
- Rac-like GTP-binding protein ARAC1
- Rac-like GTP-binding protein ARAC6
- Brefeldin A-inhibited guanine nucleotide-exchange protein 5
- Rac-like GTP-binding protein ARAC8
- Rac-like GTP-binding protein ARAC10
- Rac-like GTP-binding protein ARAC11
- Rac-like GTP-binding protein ARAC7
Sequence:
MENNNLGLRFRKLPRQPLALPKLDPLLDENLEQWPHLNQLVQCYGTEWVKDVNKYGHYENIRPDSFQTQIFEGPDTDTETEIRLASARSATIEEDVASISGRPFSDPGSSKHFGQPPLPAYEPAFDWENERAMIFGQRTPESPAASYSSGLKISVRVLSLAFQSGLVEPFFGSIALYNQERKEKLSEDFYFQIQPTEMQDAKLSSENRGVFYLDAPSASVCLLIQLEKTATEEGGVTSSVYSRKEPVHLTEREKQKLQVWSRIMPYRESFAWAVVPLFDNNLTTNTGESASPSSPLAPSMTASSSHDGVYEPIAKITSDGKQGYSGGSSVVVEISNLNKVKESYSEESIQDPKRKVHKPVKGVLRLEIEKHRNGHGDFEDLSENGSIINDSLDPTDRLSDLTLMKCPSSSSGGPRNGCSKWNSEDAKDVSRNLTSSCGTPDLNCYHAFDFCSTTRNEPFLHLFHCLYVYPVAVTLSRKRNPFIRVELRKDDTDIRKQPLEAIYPREPGVSLQKWVHTQVAVGARAASYHDEIKVSLPATWTPSHHLLFTFFHVDLQTKLEAPRPVVVGYASLPLSTYIHSRSDISLPVMRELVPHYLQESTKERLDYLEDGKNIFKLRLRLCSSLYPTNERVRDFCLEYDRHTLQTRPPWGSELLQAINSLKHVDSTALLQFLYPILNMLLHLIGNGGETLQVAAFRAMVDILTRVQQVSFDDADRNRFLVTYVDYSFDDFGGNQPPVYPGLATVWGSLARSKAKGYRVGPVYDDVLSMAWFFLELIVKSMALEQARLYDHNLPTGEDVPPMQLKESVFRCIMQLFDCLLTEVHERCKKGLSLAKRLNSSLAFFCYDLLYIIEPCQVYELVSLYMDKFSGVCQSVLHECKLTFLQIISDHDLFVEMPGRDPSDRNYLSSILIQELFLSLDHDELPLRAKGARILVILLCKHEFDARYQKAEDKLYIAQLYFPFVGQILDEMPVFYNLNATEKREVLIGVLQIVRNLDDTSLVKAWQQSIARTRLYFKLMEECLILFEHKKAADSILGGNNSRGPVSEGAGSPKYSERLSPAINNYLSEASRQEVRLEGTPDNGYLWQRVNSQLASPSQPYSLREALAQAQSSRIGASAQALRESLHPILRQKLELWEENVSATVSLQVLEITENFSSMAASHNIATDYGKLDCITTILTSFFSRNQSLAFWKAFFPIFNRIFDLHGATLMARENDRFLKQIAFHLLRLAVYRNDSVRKRAVIGLQILVKSSLYFMQTARLRALLTITLSELMSDVQVTHMKSDNTLEESGEARRLQQSLSEMADEAKSVNLLRECGLPDDTLLIIPEKFTENRWSWAEVKHLSDSLVLALDASLGHALLGSVMAMDRYAAAESFYKLGMAFAPVPDLHIMWLLHLCDAHQEMQSWAEAAQCAVAVAGVIMQALVARNDGVWSKDHVSALRKICPMVSGEFTTEASAAEVEGYGASKLTVDSAVKYLQLANKLFSQAELYHFCASILELVIPVYKSRKAYGQLAKCHTLLTNIYESILDQESNPIPFIDATYYRVGFYGEKFGKLDRKEYVYREPRDVRLGDIMEKLSHIYESRMDSNHILHIIPDSRQVKAEDLQAGVCYLQITAVDAVMEDEDLGSRRERIFSLSTGSVRARVFDRFLFDTPFTKNGKTQGGLEDQWKRRTVLQTEGSFPALVNRLLVTKSESLEFSPVENAIGMIETRTTALRNELEEPRSSDGDHLPRLQSLQRILQGSVAVQVNSGVLSVCTAFLSGEPATRLRSQELQQLIAALLEFMAVCKRAIRVHFRLIGEEDQEFHTQLVNGFQSLTAELSHYIPAILSEL