25GF: KICSTOR complex protein kaptin

Cryo-EM structure of the human KPTN-ITFG2-C12orf66-SZT2(2189-3432) complex. Determined by electron microscopy at 3.81 Å resolution. Released 26 Aug 2026.

Method: Electron microscopy
Resolution: 3.81 Å
Organism: Homo sapiens
Chains: 4
Atoms: 17,469
Mol. weight: 285.99 kDa
Released: 26 Aug 2026

Explore 25GF in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

25GF contains 80 α-helices and 107 β-strands across 4 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: 8 helices, 28 β-strands

Element	Residues	Length	Sheet
β-strand	14-21	8	1
β-strand	31-34	4	2
β-strand	40-44	5	2
β-strand	50-58	9	2
β-strand	61-69	9	2
β-strand	79-87	9	3
α-helix	88-89	2
β-strand	95-102	8	3
α-helix	109-110	2
β-strand	111-117	7	3
β-strand	135-138	4	3
β-strand	143-153	11	4
β-strand	156-165	10	4
β-strand	169-174	6	4
β-strand	183-185	3	4
α-helix	187-189	3
β-strand	201-208	8	5
α-helix	209	1
β-strand	214-221	8	5
β-strand	225-232	8	5
β-strand	237-245	9	5
β-strand	250-257	8	6
β-strand	273-279	7	6
β-strand	285-287	3	6
α-helix	290-293	4
β-strand	298-300	3	6
β-strand	310-316	7	7
β-strand	325-330	6	7
β-strand	334-340	7	7
α-helix	343-345	3
α-helix	349-351	3
β-strand	354-361	8	7
β-strand	366-372	7	1
β-strand	381-386	6	1
β-strand	389-395	7	1
α-helix	397-421	25

Chain B: 6 helices, 32 β-strands

Element	Residues	Length	Sheet
β-strand	2-4	3	10
β-strand	9-13	5	11
β-strand	23-26	4	12
β-strand	35-40	6	12
β-strand	44-48	5	12
β-strand	57-60	4	12
β-strand	65-71	7	13
β-strand	80-85	6	13
β-strand	89-93	5	13
β-strand	114-115	2	12
β-strand	119-122	4	13
β-strand	127-133	7	14
β-strand	142-147	6	14
β-strand	151-158	8	14
β-strand	170-178	9	14
β-strand	186-190	5	15
β-strand	196-202	7	15
β-strand	206-210	5	15
α-helix	211-212	2
β-strand	240-244	5	15
β-strand	256-262	7	16
β-strand	264	1	17
α-helix	272-273	2
β-strand	275-280	6	16
β-strand	284-290	7	16
β-strand	295-302	8	16
β-strand	307-313	7	10
β-strand	320	1	17
α-helix	321	1
β-strand	322-327	6	10
β-strand	331-335	5	10
β-strand	341-345	5	10
β-strand	350-358	9	11
β-strand	366-373	8	11
β-strand	377-381	5	11
α-helix	394-398	5
α-helix	402-410	9
α-helix	418-429	12

Chain C: 47 helices, 40 β-strands

Element	Residues	Length	Sheet
β-strand	2203	1	18
α-helix	2205-2211	7
α-helix	2216-2218	3
β-strand	2220-2225	6	19
α-helix	2228-2233	6
α-helix	2234-2245	12
β-strand	2250	1	19
β-strand	2254	1	18
α-helix	2259-2261	3
α-helix	2275-2277	3
β-strand	2278-2283	6	19
β-strand	2287	1	20
β-strand	2290	1	20
β-strand	2293-2302	10	19
α-helix	2307	1
β-strand	2308	1	19
α-helix	2309	1
α-helix	2311-2313	3
α-helix	2314-2318	5
α-helix	2327-2329	3
β-strand	2337-2339	3	19
β-strand	2354-2363	10	19
α-helix	2367-2386	20
α-helix	2387-2391	5
β-strand	2397-2398	2	21
α-helix	2500-2511	12
β-strand	2517-2518	2	21
α-helix	2520	1
α-helix	2521-2525	5
α-helix	2526-2535	10
β-strand	2541-2547	7	22
α-helix	2554-2568	15
β-strand	2573-2579	7	22
α-helix	2580	1
β-strand	2588-2590	3	22
β-strand	2608-2613	6	22
α-helix	2615-2618	4
α-helix	2624-2625	2
β-strand	2630	1	23
α-helix	2633-2634	2
β-strand	2635	1	24
β-strand	2644	1	24
β-strand	2649-2655	7	22
β-strand	2658-2664	7	22
β-strand	2666	1	23
α-helix	2668-2699	32
α-helix	2703-2705	3
α-helix	2729-2734	6
α-helix	2738-2740	3
α-helix	2789-2823	35
β-strand	2832	1	25
α-helix	2834-2842	9
β-strand	2845-2853	9	26
α-helix	2858-2863	6
α-helix	2907-2927	21
β-strand	2930-2931	2	26
α-helix	2933	1
β-strand	2934	1	25
α-helix	2935-2937	3
β-strand	2981-2987	7	26
β-strand	2990-2999	10	26
β-strand	3002-3011	10	26
α-helix	3012-3014	3
α-helix	3023-3038	16
α-helix	3042-3058	17
α-helix	3072-3081	10
β-strand	3092-3101	10	27
α-helix	3107-3116	10
α-helix	3118-3121	4
β-strand	3124-3130	7	27
β-strand	3133-3152	20	27
β-strand	3158-3171	14	27
α-helix	3183-3185	3
β-strand	3186-3196	11	27
α-helix	3249-3283	35
α-helix	3301-3308	8
β-strand	3312-3315	4	28
α-helix	3321-3323	3
α-helix	3324-3327	4
α-helix	3331-3344	14
α-helix	3346-3348	3
β-strand	3349-3353	5	28
β-strand	3359-3365	7	28
β-strand	3372-3379	8	28
β-strand	3385-3391	7	28
α-helix	3397-3399	3
α-helix	3407-3431	25

Chain D: 19 helices, 7 β-strands

Element	Residues	Length	Sheet
α-helix	13-25	13
α-helix	30-43	14
β-strand	47	1	8
α-helix	49-68	20
α-helix	90-100	11
α-helix	102-105	4
β-strand	113	1	8
α-helix	116-149	34
α-helix	157-171	15
α-helix	181-205	25
α-helix	209-233	25
α-helix	253-272	20
α-helix	274-277	4
α-helix	283-290	8
α-helix	297-307	11
β-strand	312-317	6	9
α-helix	338-340	3
α-helix	342-345	4
β-strand	348-352	5	9
α-helix	361-370	10
α-helix	372-375	4
β-strand	381-386	6	9
β-strand	391-399	9	9
β-strand	402-408	7	9
α-helix	417-430	14
α-helix	432-437	6

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
KICSTOR complex protein kaptin	A	protein	437	Homo sapiens	Q9Y664 (AlphaFold model)
KICSTOR subunit 2	D	protein	445	Homo sapiens	Q96MD2 (AlphaFold model)
KICSTOR complex protein ITFG2	B	protein	447	Homo sapiens	Q969R8 (AlphaFold model)
KICSTOR complex protein SZT2	C	protein	1245	Homo sapiens	Q5T011 (AlphaFold model)

Sequence of entity 1 (A), FASTA

>25GF_1 KICSTOR complex protein kaptin (chains A)
GMMGEAAVAAGPCPLREDSFTRFSSQSNVYGLAGGAGGRGELLAATLKGKVLGFRYQDLR
QKIRPVAKELQFNYIPVDAEIVSIDTFNKSPPKRGLVVGITFIKDSGDKGSPFLNIYCDY
EPGSEYNLDSIAQSCLNLELQFTPFQLCHAEVQVGDQLETVFLLSGNDPAIHLYKENEGL
HQFEEQPVENLFPELTNLTSSVLWLDVHNFPGTSRRLSALGCQSGYVRVAHVDQRSREVL
QMWSVLQDGPISRVIVFSLSAAKETKDRPLQDEYSVLVASMLEPAVVYRDLLNRGLEDQL
LLPGSDQFDSVLCSLVTDVDLDGRPEVLVATYGQELLCYKYRGPESGLPEAQHGFHLLWQ
RSFSSPLLAMAHVDLTGDGLQELAVVSLKGVHILQHSLIQASELVLTRLRHQVEQRRRRL
QGLEDGAGAGPAENAAS

Sequence of entity 2 (D), FASTA

>25GF_2 KICSTOR subunit 2 (chains D)
MGESIPLAAPVPVEQAVLETFFSHLGIFSYDKAKDNVEKEREANKSAGGSWLSLLAALAH
LAAAEKVYHSLTYLGQKLGGQSFFSRKDSIRTIYTSLHNELKKVVTGRGALGGTAPHVEE
LLSHLSEQLCFFVQARMEIADFYEKMYTLSTQKFINAEELVGLLDAIMKKYSSRFHHPIL
SPLESSFQLEVDVLCHLLKAQAQVSEWKFLPSLVNLHSAHTKLQTWGQIFEKQRETKKHL
FGGQSQKAVQPPHLFLWLMKLKNMLLAKFSFYFHEALSRQTTASEMKTLTAKANPDFFGK
ISSFIRKYDAANVSLIFDNRGSESFQGHGYHHPHSYREAPKGVDQYPAVVSLPSDRPVMH
WPNVIMIMTDRTSDLNSLEKVVHFYDDKVQSTYFLTRPEPHFTIVIIFESKKSERDSHFI
SFLNEVSLALKNPKVFASLKPGAKG

Sequence of entity 3 (B), FASTA

>25GF_3 KICSTOR complex protein ITFG2 (chains B)
MRSVSYVQRVALEFSGSLFPHAICLGDVDNDTLNELVVGDTSGKVSVYKNDDSRPWLTCS
CQGMLTCVGVGDVCNKGKNLLVAVSAEGWFHLFDLTPAKVLDASGHHETLIGEEQRPVFK
QHIPANTKVMLISDIDGDGCRELVVGYTDRVVRAFRWEELGEGPEHLTGQLVSLKKWMLE
GQVDSLSVTLGPLGLPELMVSQPGCAYAILLCTWKKDTGSPPASEGPTDGSRETPAARDV
VLHQTSGRIHNKNVSTHLIGNIKQGHGTESSGSGLFALCTLDGTLKLMEEMEEADKLLWS
VQVDHQLFALEKLDVTGNGHEEVVACAWDGQTYIIDHNRTVVRFQVDENIRAFCAGLYAC
KEGRNSPCLVYVTFNQKIYVYWEVQLERMESTNLVKLLETKPEYHSLLQELGVDPDDLPV
TRALLHQTLYHPDQPPQCAPSSLQDPT

Sequence of entity 4 (C), FASTA

>25GF_4 KICSTOR complex protein SZT2 (chains C)
GTLDVITVMLVRNCKLTPADVEFIQPPGSLPSEVLHLALPTSCRPWLPALAWYLRQNLLI
FLHSPKYTDSNSRNHFQHPLPPQGGLPDLDIYLYNKPGGQGTGGKGVACITLAFVDEGGA
PLSLALWPPSSPGPPDPLREEEFEQLTQVIRCPVVVDSSSAQNGAPRLRLDVWEKGNISI
VQLEEKLRGAARQALADAIIELQLLPASLCTEDTPTGSLRNGSLETKSSAGRASTFPPAP
VPGEPVTPPSKAGRRSFWDMLSKTECGDLGSPKTTDDIVLDRPEDTRGRRRHKTESVRTP
GGAERAPGSDSGAQRQKRRTTQLEEGEVGTLHPVFARVAQRWMEFMVQIGCASVSRSSAH
MVSRFLLPSILSEFTALVTSMAGDTSVRIFEQHLGSEPEIFGPCSPGQLGPSPRPAAERH
LLLLGRNFLQWRRPTQQAAKAMQRFEPGGDGSSGRNAPRQRLLLLEVVDKKLQLLTYNWA
PDLGAALGRALVRLVQWQNARAHLIFCLLSQKLGLFHHYGQLDFPVRDEKEPNPFLLPTM
EVETLIRSASPPLSREQGRLSGSSRGGGPLPLDTFPFDEALRDITAARPSSVLGPVPRPP
DPVTYHGQQFLEIKMAERRELERQMKMENLFVTWQQRSTPATMPISAGELETLKQSSRLV
HYCATAMLFDPAAWLHGPPETSGPPDGQRRHRPESGSGSREAPTSCESLDVSPPGAREEP
WLKELSLAFLQQYVQYLQSIGFVLVPLRPPSPARSTSRPRAMAILGTEGRGSFSCPKTKT
DGSPKSTSSPVTTYHLQRALPGGIILMELAFQGCYFCVKQFALECSRIPMGQAVNSQLSM
LFTEECDKVRDLMHVHSFSYDFHLRLVHQHVLGAHLVLRHGYHLTTFLRHFLAHHPDGPH
FGRNHIYQGTLELPTPLIAAHQLYNYVADHASSYHMKPLRMARPGGPEHNEYALVSAWHS
SGSYLDSEGLRHQDDFDVSLLVCHCAAPFEEQGEAERHVLRLQFFVVLTSQRELFPRLTA
DMRRFRKPPRLPPEPEAPGSSAGSPGEASGLILAPGPAPLFPPLAAEVGMARARLAQLVR
LAGGHCRRDTLWKRLFLLEPPGPDRLRLGGRLALAELEELLEAVHAKSIGDIDPQLDCFL
SMTVSWYQSLIKVLLSRFPQSCRHFQSPDLGTQYLVVLNQKFTDCFVLVFLDSHLGKTSL
TVVFREPFPVQPQDSESPPAQLVSTYHHLESVINTACFTLWTRLL

Primary citation

Mechanistic insights into GATOR1 inhibition by GATOR2 and KICSTOR. Yang, A., Liang, L. To be published.

Other PDB entries of the same protein (UniProt Q9Y664 (AlphaFold model), which also has an AlphaFold model), best resolution first:

9VAN 2.9 Å, Cryo-EM structure of human full length KICSTOR complex (state 2)
9V80 2.95 Å, Cryo-EM structure of KICSTOR CCC complex (state 4)
9V86 3.04 Å, Cryo-EM structure of KICSTOR CCC complex (state 3)
9V9N 3.08 Å, Cryo-EM structure of KICSTOR CCC complex (state 5)
9V6E 3.19 Å, Cryo-EM structure of human full length KICSTOR complex (state 1)
9O5A 3.2 Å, The KICSTOR-GATOR1 complex
25GE 3.37 Å, Cryo-EM structure of the human KPTN-ITFG2-SZT2(2189-3432) complex

Browse structure collections

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