24QH: FFAR4-Gi complex with unknown density

Cryo-EM Structure of the FFAR4-Gi complex with unknown density. Determined by electron microscopy at 2.74 Å resolution. Released 8 Jul 2026.

Method: Electron microscopy
Resolution: 2.74 Å
Organism: Homo sapiens
Chains: 5
Atoms: 8,931
Mol. weight: 150.31 kDa
Released: 8 Jul 2026

Explore 24QH in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

24QH contains 33 α-helices and 61 β-strands across 5 chains. Residue ranges use author residue numbering, as in the PDB file, from PDBe. To see them in 3D, choose the Cartoon representation with Secondary structure coloring: helices, sheets and coils get different colors.

Chain A: 12 helices, 2 β-strands

Element	Residues	Length	Sheet
α-helix	36-66	31
α-helix	74-89	16
α-helix	92-101	10
α-helix	110-141	32
α-helix	156-169	14
α-helix	171-175	5
β-strand	177-183	7	15
β-strand	190-196	7	15
α-helix	201-212	12
α-helix	213-217	5
α-helix	218-243	26
α-helix	249-292	44
α-helix	302-310	9
α-helix	312-322	11

Chain B: 3 helices, 28 β-strands

Element	Residues	Length	Sheet
α-helix	5-23	19
α-helix	30-33	4
α-helix	38-39	2
β-strand	47-51	5	2
β-strand	58-63	6	3
β-strand	69-74	6	3
β-strand	78-83	6	3
β-strand	88-94	7	3
β-strand	100-105	6	4
β-strand	111-116	6	4
β-strand	120-125	6	4
β-strand	134-140	7	4
β-strand	146-153	8	5
β-strand	156-161	6	5
β-strand	166-170	5	5
β-strand	176-180	5	5
β-strand	187-192	6	6
β-strand	198-203	6	6
β-strand	207-212	6	6
β-strand	218-223	6	6
β-strand	229-234	6	7
β-strand	240-245	6	7
β-strand	250-254	5	7
β-strand	259-264	6	7
β-strand	273-278	6	8
β-strand	284-289	6	8
β-strand	294-298	5	8
β-strand	304-308	5	8
β-strand	315-320	6	2
β-strand	327-331	5	2
β-strand	336-339	4	2

Chain C: 9 helices, 6 β-strands

Element	Residues	Length	Sheet
α-helix	7-30	24
β-strand	34-40	7	1
α-helix	46-50	5
β-strand	185-190	6	1
β-strand	195-200	6	1
α-helix	208-210	3
α-helix	212-215	4
β-strand	220-226	7	1
α-helix	242-254	13
β-strand	263-269	7	1
α-helix	271-277	7
α-helix	283-285	3
α-helix	296-308	13
β-strand	319-323	5	1
α-helix	331-350	20

Chain G: 4 helices, 0 β-strands

Element	Residues	Length
α-helix	9-23	15
α-helix	30-43	14
α-helix	53-55	3
α-helix	56-58	3

Chain S: 5 helices, 25 β-strands

Element	Residues	Length	Sheet
β-strand	4-7	4	9
β-strand	11-12	2	10
β-strand	17-24	8	9
α-helix	29-31	3
β-strand	33-39	7	11
β-strand	45-51	7	11
β-strand	58-60	3	11
β-strand	68-73	6	9
α-helix	74-76	3
β-strand	78-84	7	9
α-helix	88-90	3
β-strand	92-99	8	11
β-strand	110-111	2	11
β-strand	115-117	3	11
β-strand	118-119	2	10
β-strand	140-141	2	12
β-strand	146-148	3	13
β-strand	155-161	7	12
β-strand	166	1	14
β-strand	172	1	14
β-strand	174-179	6	13
β-strand	186-190	5	13
β-strand	194-195	2	13
α-helix	196	1
β-strand	203-208	6	12
β-strand	211-216	6	12
β-strand	225-231	7	13
α-helix	237	1
β-strand	238-239	2	13
β-strand	243-246	4	13

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Guanine nucleotide-binding protein G(i) subunit alpha-1	C	protein	351	Homo sapiens	P63096 (AlphaFold model)
Guanine nucleotide-binding protein G(I)/G(S)/G(T) subunit beta-1	B	protein	337	Homo sapiens	P62873 (AlphaFold model)
Guanine nucleotide-binding protein G(I)/G(S)/G(O) subunit gamma-2	G	protein	56	Homo sapiens	P59768 (AlphaFold model)
scFv16	S	protein	247	Homo sapiens
Free fatty acid receptor 4	A	protein	361	Homo sapiens	Q5NUL3 (AlphaFold model)

Sequence of entity 1 (C), FASTA

>24QH_1 Guanine nucleotide-binding protein G(i) subunit alpha-1 (chains C)
TLSAEDKAAVERSKMIDRNLREDGEKAAREVKLLLLGAGESGKSTIVKQMKIIHEAGYSE
EECKQYKAVVYSNTIQSIIAIIRAMGRLKIDFGDSARADDARQLFVLAGAAEEGFMTAEL
AGVIKRLWKDSGVQACFNRSREYQLNDSAAYYLNDLDRIAQPNYIPTQQDVLRTRVKTTG
IVETHFTFKDLHFKMFDVGAQRSERKKWIHCFEGVTAIIFCVALSDYDLVLAEDEEMNRM
HESMKLFDSICNNKWFTDTSIILFLNKKDLFEEKIKKSPLTICYPEYAGSNTYEEAAAYI
QCQFEDLNKRKDTKEIYTHFTCSTDTKNVQFVFDAVTDVIIKNNLKDCGLF

Sequence of entity 2 (B), FASTA

>24QH_2 Guanine nucleotide-binding protein G(I)/G(S)/G(T) subunit beta-1 (chains B)
LDQLRQEAEQLKNQIRDARKACADATLSQITNNIDPVGRIQMRTRRTLRGHLAKIYAMHW
GTDSRLLVSASQDGKLIIWDSYTTNKVHAIPLRSSWVMTCAYAPSGNYVACGGLDNICSI
YNLKTREGNVRVSRELAGHTGYLSCCRFLDDNQIVTSSGDTTCALWDIETGQQTTTFTGH
TGDVMSLSLAPDTRLFVSGACDASAKLWDVREGMCRQTFTGHESDINAICFFPNGNAFAT
GSDDATCRLFDLRADQELMTYSHDNIICGITSVSFSKSGRLLLAGYDDFNCNVWDALKAD
RAGVLAGHDNRVSCLGVTDDGMAVATGSWDSFLKIWN

Sequence of entity 3 (G), FASTA

>24QH_3 Guanine nucleotide-binding protein G(I)/G(S)/G(O) subunit gamma-2 (chains G)
SIAQARKLVEQLKMEANIDRIKVSKAAADLMAYCEAHAKEDPLLTPVPASENPFRE

Sequence of entity 4 (S), FASTA

>24QH_4 scFv16 (chains S)
DVQLVESGGGLVQPGGSRKLSCSASGFAFSSFGMHWVRQAPEKGLEWVAYISSGSGTIYY
ADTVKGRFTISRDDPKNTLFLQMTSLRSEDTAMYYCVRSIYYYGSSPFDFWGQGTTLTVS
SGGGGSGGGGSGGGGSDIVMTQATSSVPVTPGESVSISCRSSKSLLHSNGNTYLYWFLQR
PGQSPQLLIYRMSNLASGVPDRFSGSGSGTAFTLTISRLEAEDVGVYYCMQHLEYPLTFG
AGTKLEL

Sequence of entity 5 (A), FASTA

>24QH_5 Free fatty acid receptor 4 (chains A)
MSPECARAAGDAPLRSLEQANRTRFPFFSDVKGDHRLVLAAVETTVLVLIFAVSLLGNVC
ALVLVARRRRRGATACLVLNLFCADLLFISAIPLVLAVRWTEAWLLGPVACHLLFYVMTL
SGSVTILTLAAVSLERMVCIVHLQRGVRGPGRRARAVLLALIWGYSAVAALPLCVFFRVV
PQRLPGADQEISICTLIWPTIPGEISWDVSFVTLNFLVPGLVIVISYSKILQITKASRKR
LTVSLAYSESHQIRVSQQDFRLFRTLFLLMVSFFIMWSPIIITILLILIQNFKQDLVIWP
SLFFWVVAFTFANSALNPILYNMTLCRNEWKKIFCCFWFPEKGAILTDTSVKRNDLSIIS
G

Primary citation

Cryo-EM Structure of the apo FFAR4-Gi complex. Chen, G., Wu, Z.S., Qiu, C. To be published.

Other PDB entries of the same protein (UniProt P63096 (AlphaFold model), which also has an AlphaFold model), best resolution first:

6CRK 2.0 Å, Heterotrimeric G-protein in complex with an antibody fragment
3UMR 2.04 Å, Crystal structure of the G202D mutant of human G-alpha-i1
9P7Z 2.1 Å, NTSR1-Gi-NTS(8-13) Complex in the Canonical, AHD Open State (C-Open-Apo)
2OM2 2.2 Å, Crystal Structure Of Human G[alpha]i1 Bound To The Goloco Motif Of Rgs14
8YN9 2.3 Å, Cryo-EM structure of histamine H4 receptor in complex with histamine and Gi
9HYI 2.3 Å, DP81-bound serotonin 5-HT1A receptor - Gi Protein Complex
9O36 2.3 Å, CryoEM structure of mu-opioid receptor - Gi protein complex bound to fluornitrazene (FNZ)
9P80 2.3 Å, NTSR1-Gi-NTS(8-13) Complex in the Non-Canonical, AHD Open State (NC-Open-Apo)
8XXV 2.33 Å, Cryo-EM Structure of the Prostaglandin D2 Receptor 2-indomethacin Coupled to G Protein
3UMS 2.34 Å, Crystal structure of the G202A mutant of human G-alpha-i1
3ONW 2.38 Å, Structure of a G-alpha-i1 mutant with enhanced affinity for the RGS14 GoLoco motif.
20ZG 2.4 Å, Cryo-EM structure of the human neurotensin receptor 1 (hNTSR1)-Gi1 complex in the…

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