Ci protein

Ci protein, short for Cubitus interruptus, is a zinc finger containing transcription factor^[1] involved in the Hedgehog signaling pathway.^[2] In the absence of a signal to the Hedgehog signaling pathway, the Ci protein is cleaved and destroyed in proteasomes. It isn't, however, completely destroyed; part of the protein survives and acts as a repressor in the nucleus, keeping genes responsive to the Hedgehog signal silent.

Degradation of Ci

The degradation of Ci protein depends on a large multiprotein complex, which contains a serine/threonine kinase of unknown function, an anchoring protein that binds to microtubules (to keep the Ci protein out of the nucleus) and an adaptor protein.^[3] When the Hedgehog signaling pathway is turned on, the Ci proteolysis is suppressed and the unprocessed CI protein enters the nucleus, where it activates the transcription of its target genes.

Target genes

The Wingless protein in Drosophila, which is crucial to the embryogenesis of the fruit fly, and acts through the Wnt signaling pathway.
The Patched receptor protein of the Hedgehog signaling pathway, which production acts as a negative feedback, since the resulting increase in Patched protein on the cell surface inhibits the Hedgehog pathway.^[4]

References

↑ Von Ohlen T, Lessing D, Nusse R, Hooper JE (March 1997). "Hedgehog signaling regulates transcription through cubitus interruptus, a sequence-specific DNA binding protein". Proc. Natl. Acad. Sci. U.S.A. 94 (6): 2404–9. doi:10.1073/pnas.94.6.2404. PMC 20100. PMID 9122207.
↑ Cohen MM (November 2003). "The hedgehog signaling network". Am. J. Med. Genet. A 123 (1): 5–28. doi:10.1002/ajmg.a.20495. PMID 14556242.
↑ Jiang J (September 2002). "Degrading Ci: who is Cul-pable?". Genes Dev. 16 (18): 2315–21. doi:10.1101/gad.1027902. PMID 12231619.
↑ Hepker J, Wang QT, Motzny CK, Holmgren R, Orenic TV (January 1997). "Drosophila cubitus interruptus forms a negative feedback loop with patched and regulates expression of Hedgehog target genes". Development 124 (2): 549–58. PMID 9053330.

External links

ci protein, Drosophila at the US National Library of Medicine Medical Subject Headings (MeSH)
Drosophila cubitus interruptus - The Interactive Fly

Transcription factors and intracellular receptors

(1) Basic domains

(1.1) Basic leucine zipper (bZIP)	Activating transcription factor AATF 1 2 3 4 5 6 7 AP-1 c-Fos FOSB FOSL1 FOSL2 JDP2 c-Jun JUNB JunD BACH 1 2 BATF BLZF1 C/EBP α β γ δ ε ζ CREB 1 3 L1 CREM DBP DDIT3 GABPA HLF MAF B F G K NFE 2 L1 L2 L3 NFIL3 NRL NRF 1 2 3 XBP1

(1.2) Basic helix-loop-helix (bHLH)	ATOH1 AhR AHRR ARNT ASCL1 BHLH 2 3 9 ARNTL ARNTL ARNTL2 CLOCK EPAS1 FIGLA HAND 1 2 HES 5 6 HEY 1 2 L HES1 HIF 1A 3A ID 1 2 3 4 LYL1 MESP2 MXD4 MYCL1 MYCN Myogenic regulatory factors MyoD Myogenin MYF5 MYF6 Neurogenins 1 2 3 NeuroD 1 2 NPAS 1 2 3 OLIG 1 2 Pho4 Scleraxis SIM 1 2 TAL 1 2 Twist USF1

(1.3) bHLH-ZIP	AP-4 MAX MXD3 MITF MNT MLX MXI1 Myc SREBP 1 2

(1.4) NF-1	NFI A B C X SMAD R-SMAD 1 2 3 5 9 I-SMAD 6 7 4)

(1.5) RF-X	RFX 1 2 3 4 5 6 ANK

(1.6) Basic helix-span-helix (bHSH)	AP-2 α β γ δ ε

(2) Zinc finger DNA-binding domains

(2.1) Nuclear receptor (Cys₄)

subfamily 1	Thyroid hormone α β CAR FXR LXR α β PPAR α β/δ γ PXR RAR α β γ ROR α β γ Rev-ErbA α β VDR

subfamily 2	COUP-TF (I II Ear-2 HNF4 α γ PNR RXR α β γ Testicular receptor 2 4 TLX

subfamily 3	Steroid hormone Androgen Estrogen α β Glucocorticoid Mineralocorticoid Progesterone Estrogen related α β γ

subfamily 4	NUR NGFIB NOR1 NURR1

subfamily 5	LRH-1 SF1

subfamily 6	GCNF

subfamily 0	DAX1 SHP

(2.2) Other Cys₄

GATA
- 1
- 2
- 3
- 4
- 5
- 6
MTA
- 1
- 2
- 3
TRPS1

(2.3) Cys₂His₂

General transcription factors
- TFIIA
- TFIIB
- TFIID
- TFIIE
  - 1
  - 2
- TFIIF
- 1
- 2
  - TFIIH
  - 1
  - 2
  - 4
  - 2I
  - 3A
  - 3C1
  - 3C2

ATBF1
BCL
- 6
- 11A
- 11B
CTCF
E4F1
EGR
- 1
- 2
- 3
- 4
ERV3
GFI1
GLI-Krüppel family
- 1
- 2
- 3
- REST
- S1
- S2
- YY1
HIC
- 1
- 2
HIVEP
- 1
- 2
- 3
IKZF
- 1
- 2
- 3
ILF
- 2
- 3
KLF
- 1
- 2
- 3
- 4
- 5
- 6
- 7
- 8
- 9
- 10
- 11
- 12
- 13
- 14
- 15
- 17
MTF1
MYT1
OSR1
PRDM9
SALL
- 1
- 2
- 3
- 4
SP
- 1
- 2
- 4
- 7
- 8
TSHZ3
WT1
Zbtb7
- 7A
- 7B
ZBTB
- 11
- 16
- 17
- 20
- 32
- 33
- 40
zinc finger
- 3
- 7
- 9
- 10
- 19
- 22
- 24
- 33B
- 34
- 35
- 41
- 43
- 44
- 51
- 74
- 143
- 146
- 148
- 165
- 202
- 217
- 219
- 238
- 239
- 259
- 267
- 268
- 281
- 295
- 300
- 318
- 330
- 346
- 350
- 365
- 366
- 384
- 423
- 451
- 452
- 471
- 593
- 638
- 644
- 649
- 655

(2.4) Cys₆

HIVEP1

(2.5) Alternating composition

AIRE
DIDO1
GRLF1
ING
- 1
- 2
- 4
JARID
- 1A
- 1B
- 1C
- 1D
- 2
JMJD1B

(2.6) WRKY

WRKY

(3) Helix-turn-helix domains

(3.1) Homeodomain	ARX CDX 1 2 CRX CUTL1 DBX 1 2 DLX 3 4 5 EMX 1 2 EN 1 2 FHL 1 2 3 HESX1 HHEX HLX Homeobox A1 A2 A3 A4 A5 A7 A9 A10 A11 A13 B1 B2 B3 B4 B5 B6 B7 B8 B9 B13 C4 C5 C6 C8 C9 C10 C11 C12 C13 D1 D3 D4 D8 D9 D10 D11 D12 D13 HOPX IRX 1 2 3 4 5 6 MKX LMX 1A 1B MEIS 1 2 MEOX2 MNX1 MSX 1 2 NANOG NKX 2-1 2-2 2-3 2-5 3-1 3-2 6-1 6-2 NOBOX PBX 1 2 3 PHF 1 3 6 8 10 16 17 20 21A PHOX 2A 2B PITX 1 2 3 POU domain PIT-1 BRN-3: A B C Octamer transcription factor: 1 2 3/4 6 7 11 OTX 1 2 PDX1 SATB2 SHOX2 SIX 1 2 3 4 5 VAX1 ZEB 1 2

(3.2) Paired box	PAX 1 2 3 4 5 6 7 8 9 PRRX 1 2 RAX

(3.3) Fork head / winged helix	E2F 1 2 3 4 5 FOX proteins A1 A2 A3 C1 C2 D3 D4 E1 E3 F1 G1 H1 I1 J1 J2 K1 K2 L2 M1 N1 N3 O1 O3 O4 P1 P2 P3 P4

(3.4) Heat shock factors	HSF 1 2 4

(3.5) Tryptophan clusters	ELF 2 4 5 EGF ELK 1 3 4 ERF ETS 1 2 ERG SPIB ETV 1 4 5 6 FLI1 Interferon regulatory factors 1 2 3 4 5 6 7 8 MYB MYBL2

(3.6) TEA domain	transcriptional enhancer factor 1 2 3 4

(4) β-Scaffold factors with minor groove contacts

(4.1) Rel homology region	NF-κB NFKB1 NFKB2 REL RELA RELB NFAT C1 C2 C3 C4 5

(4.2) STAT	STAT 1 2 3 4 5 6

(4.3) p53	p53 TBX 1 2 3 5 19 21 22 TBR1 TBR2 TFT MYRF TP63

(4.4) MADS box	Mef2 A B C D SRF

(4.6) TATA-binding proteins	TBP TBPL1

(4.7) High-mobility group	BBX HMGB 1 2 3 4 HMGN 1 2 3 4 HNF 1A 1B LEF1 SOX 1 2 3 4 5 6 8 9 10 11 12 13 14 15 18 21 SRY SSRP1 TCF 3 4 TOX 1 2 3 4

(4.9) Grainyhead	TFCP2

(4.10) Cold-shock domain	CSDA YBX1

(4.11) Runt	CBF CBFA2T2 CBFA2T3 RUNX1 RUNX2 RUNX3 RUNX1T1

(0) Other transcription factors

(0.2) HMGI(Y)	HMGA 1 2 HBP1

(0.3) Pocket domain	Rb RBL1 RBL2

(0.5) AP-2/EREBP-related factors	Apetala 2 EREBP B3

(0.6) Miscellaneous	ARID 1A 1B 2 3A 3B 4A CAP IFI 16 35 MLL 2 3 T1 MNDA NFY A B C Rho/Sigma

see also transcription factor/coregulator deficiencies

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