9K3H: PDB entry 9K3H

Cryo-EM structure of the unliganded human melanocortin receptor 5 (MC5R)-Gs complex. Determined by electron microscopy at 2.86 Å resolution. Released 6 Aug 2025.

Method: Electron microscopy
Resolution: 2.86 Å
Organisms: Homo sapiens, synthetic construct, Bos taurus
Chains: 5
Atoms: 8,835
Mol. weight: 175.57 kDa
Released: 6 Aug 2025

Explore 9K3H in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

9K3H contains 33 α-helices and 57 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, 6 β-strands

Element	Residues	Length	Sheet
α-helix	18-22	5
α-helix	23-37	15
β-strand	40-47	8	1
α-helix	53-63	11
β-strand	207-213	7	1
β-strand	218-224	7	1
α-helix	236-238	3
β-strand	243-249	7	1
α-helix	267-277	11
α-helix	280-282	3
β-strand	286-292	7	1
α-helix	294-302	9
α-helix	308-311	4
α-helix	313-315	3
α-helix	326-327	2
α-helix	332-350	19
β-strand	359-360	2	1
α-helix	371-390	20

Chain B: 4 helices, 28 β-strands

Element	Residues	Length	Sheet
α-helix	4-24	21
α-helix	30-35	6
α-helix	38-40	3
β-strand	46-51	6	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	121-125	5	4
β-strand	134-139	6	4
β-strand	146-153	8	5
β-strand	156-161	6	5
β-strand	165-170	6	5
β-strand	178-181	4	5
β-strand	191-192	2	6
β-strand	198-202	5	6
β-strand	207-212	6	6
β-strand	218-223	6	6
β-strand	229-234	6	7
β-strand	241-245	5	7
β-strand	250-253	4	7
β-strand	263-264	2	7
α-helix	272-273	2
β-strand	275-277	3	8
β-strand	284-288	5	8
β-strand	296-298	3	8
β-strand	304-306	3	8
β-strand	315-320	6	2
β-strand	327-331	5	2
β-strand	336-340	5	2

Chain G: 4 helices, 0 β-strands

Element	Residues	Length
α-helix	10-12	3
α-helix	13-24	12
α-helix	30-42	13
α-helix	53-55	3

Chain R: 11 helices, 0 β-strands

Element	Residues	Length
α-helix	41-63	23
α-helix	70-98	29
α-helix	108-110	3
α-helix	111-145	35
α-helix	147-152	6
α-helix	156-179	24
α-helix	188-220	33
α-helix	233-263	31
α-helix	268-274	7
α-helix	277-294	18
α-helix	300-310	11

Chain S: 2 helices, 23 β-strands

Element	Residues	Length	Sheet
β-strand	3-7	5	9
β-strand	10-12	3	10
β-strand	17-25	9	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	69-73	5	9
α-helix	74-76	3
β-strand	78-84	7	9
β-strand	92-94	3	10
β-strand	95-99	5	11
β-strand	111	1	11
β-strand	115-119	5	10
β-strand	140-141	2	12
β-strand	146-148	3	13
β-strand	155-161	7	12
β-strand	174-179	6	13
β-strand	185-190	6	13
β-strand	194-195	2	13
β-strand	203-207	5	12
β-strand	211-216	6	12
β-strand	225-231	7	13
β-strand	239	1	13
β-strand	243-246	4	13

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Melanocortin receptor 5,Melanocortin receptor 5,Melanocortin receptor 5,LgBiT subunit	R	protein	498	Homo sapiens, synthetic construct	P33032 (AlphaFold model)
Guanine nucleotide-binding protein G(i) subunit alpha-1,Guanine nucleotide-binding protein G(s)…	A	protein	361	Homo sapiens	P63092 (AlphaFold model), P63096 (AlphaFold model)
Guanine nucleotide-binding protein G(I)/G(S)/G(T) subunit beta-1,Guanine nucleotide-binding…	B	protein	371	Homo sapiens, synthetic construct	P62873 (AlphaFold model)
Guanine nucleotide-binding protein G(I)/G(S)/G(O) subunit gamma-2	G	protein	71	Bos taurus	P63212
scFv16	S	protein	285	synthetic construct

Sequence of entity 1 (R), FASTA

>9K3H_1 Melanocortin receptor 5,Melanocortin receptor 5,Melanocortin receptor 5,LgBiT subunit (chains R)
MNSSFHLHFLDLNLNATEGNLSGPNVKNKSSPCEDMGIAVEVFLTLGVISLLENILVIGA
IVKNKNLHSPMYFFVCSLAVADMLVSMSSAWETITIYLLNNKHLVIADAFVRHIDNVFDS
MICISVVASMCSLLAIAVDRYVTIFYALRYHHIMTARRSGAIIAGIWAFCTGCGIVFILY
SESTYVILCLISMFFAMLFLLVSLYIHMFLLARTHVKRIAALPGASSARQRTSMQGAVTV
TMLLGVFTVCWAPFFLHLTLMLSCPQNLYCSRFMSHFNMYLILIMCNSVMDPLIYAFRSQ
EMRKTFKEIICCRGFRIACSFPRRDGSSGGGGSGGGGSSGVFTLEDFVGDWEQTAAYNLD
QVLEQGGVSSLLQNLAVSVTPIQRIVRSGENALKIDIHVIIPYEGLSADQMAQIEEVFKV
VYPVDDHHFKVILPYGTLVIDGVTPNMLNYFGRPYEGIAVFDGKKITVTGTLWNGNKIID
ERLITPDGSMLFRVTINS

Sequence of entity 2 (A), FASTA

>9K3H_2 Guanine nucleotide-binding protein G(i) subunit alpha-1,Guanine nucleotide-binding protein G(s) subunit alpha isoforms short (chains A)
MGCTLSAEDKAAVERSKMIEKQLQKDKQVYRATHRLLLLGADNSGKSTIVKQMRIYHVNG
YSEEECKQYKAVVYSNTIQSIIAIIRAMGRLKIDFGDSARADDARQLFVLAGAAEEGFMT
AELAGVIKRLWKDSGVQACFNRSREYQLNDSAAYYLNDLDRIAQPNYIPTQQDVLRTRVK
TSGIFETKFQVDKVNFHMFDVGAQRDERRKWIQCFNDVTAIIFVVDSSDYNRLQEALNDF
KSIWNNRWLRTISVILFLNKQDLLAEKVLAGKSKIEDYFPEFARYTTPEDATPEPGEDPR
VTRAKYFIRDEFLRISTASGDGRHYCYPHFTCSVDTENARRIFNDCRDIIQRMHLRQYEL
L

Sequence of entity 3 (B), FASTA

>9K3H_3 Guanine nucleotide-binding protein G(I)/G(S)/G(T) subunit beta-1,Guanine nucleotide-binding protein G(I)/G(S)/G(T) subunit beta-1,Guanine nucleotide-binding protein G(I)/G(S)/G(T) subunit beta-1,HiBiT (chains B)
MGSLLQSELDQLRQEAEQLKNQIRDARKACADATLSQITNNIDPVGRIQMRTRRTLRGHL
AKIYAMHWGTDSRLLVSASQDGKLIIWDSYTTNKVHAIPLRSSWVMTCAYAPSGNYVACG
GLDNICSIYNLKTREGNVRVSRELAGHTGYLSCCRFLDDNQIVTSSGDTTCALWDIETGQ
QTTTFTGHTGDVMSLSLAPDTRLFVSGACDASAKLWDVREGMCRQTFTGHESDINAICFF
PNGNAFATGSDDATCRLFDLRADQELMTYSHDNIICGITSVSFSKSGRLLLAGYDDFNCN
VWDALKADRAGVLAGHDNRVSCLGVTDDGMAVATGSWDSFLKIWNGSSGGGGSGGGGSSG
VSGWRLFKKIS

Sequence of entity 4 (G), FASTA

>9K3H_4 Guanine nucleotide-binding protein G(I)/G(S)/G(O) subunit gamma-2 (chains G)
MASNNTASIAQARKLVEQLKMEANIDRIKVSKAAADLMAYCEAHAKEDPLLTPVPASENP
FREKKFFCAIL

Sequence of entity 5 (S), FASTA

>9K3H_5 scFv16 (chains S)
MLLVNQSHQGFNKEHTSKMVSAIVLYVLLAAAAHSAFAVQLVESGGGLVQPGGSRKLSCS
ASGFAFSSFGMHWVRQAPEKGLEWVAYISSGSGTIYYADTVKGRFTISRDDPKNTLFLQM
TSLRSEDTAMYYCVRSIYYYGSSPFDFWGQGTTLTVSAGGGGSGGGGSGGGGSADIVMTQ
ATSSVPVTPGESVSISCRSSKSLLHSNGNTYLYWFLQRPGQSPQLLIYRMSNLASGVPDR
FSGSGSGTAFTLTISRLEAEDVGVYYCMQHLEYPLTFGAGTKLEL

Primary citation

Structural basis for the constitutive activity of the melanocortin receptor family. Feng, W., Zhou, Q., Zheng, C. et al. Structure (2025) 33:1074-1087.e5. DOI 10.1016/j.str.2025.03.004 · PubMed

Other PDB entries of the same protein (UniProt P33032 (AlphaFold model), which also has an AlphaFold model), best resolution first:

8IOD 2.59 Å, Cryo-EM structure of the PG-901-bound human melanocortin receptor 5 (MC5R)-Gs complex
8INR 2.73 Å, Cryo-EM structure of the alpha-MSH-bound human melanocortin receptor 5 (MC5R)-Gs complex

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