4IW4: Serine protease domain of MASP-3

Crystal structure of the serine protease domain of MASP-3 in complex with ecotin. Determined by X-ray diffraction at 3.2 Å resolution. Released 19 Jun 2013.

Method: X-ray diffraction
Resolution: 3.2 Å
Organisms: Escherichia coli, Homo sapiens
Chains: 4
Atoms: 5,735
Mol. weight: 93.41 kDa
Released: 19 Jun 2013

Explore 4IW4 in 3D Show helices and sheets RCSB PDB PDBe

Secondary structure: helices and β-sheets

4IW4 contains 32 α-helices and 75 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 C: 4 helices, 16 β-strands

Element	Residues	Length	Sheet
α-helix	13-17	5
β-strand	20-25	6	1
α-helix	27-29	3
α-helix	33-35	3
β-strand	36-48	13	2
β-strand	53-54	2	1
β-strand	55	1	3
β-strand	56	1	1
β-strand	57	1	4
β-strand	58-63	6	1
β-strand	70-83	14	1
β-strand	86	1	5
β-strand	93-98	6	2
β-strand	99	1	3
β-strand	106-108	3	2
β-strand	115-120	6	1
β-strand	124-132	9	2
β-strand	137-138	2	2
α-helix	139	1
β-strand	140	1	6

Chain D: 8 helices, 16 β-strands

Element	Residues	Length	Sheet
α-helix	7-9	3
α-helix	13-17	5
β-strand	20-25	6	6
α-helix	27-29	3
α-helix	33-35	3
β-strand	36-47	12	2
β-strand	53-54	2	7
β-strand	55	1	8
β-strand	57	1	9
β-strand	58-64	7	6
β-strand	69-75	7	6
α-helix	79-80	2
β-strand	81-83	3	7
β-strand	86	1	10
β-strand	94-98	5	2
β-strand	99	1	8
α-helix	102-105	4
β-strand	106-108	3	2
β-strand	115-120	6	6
β-strand	124-132	9	2
α-helix	133	1
β-strand	137-138	2	2
α-helix	139	1
β-strand	140-141	2	1

Chain E: 9 helices, 21 β-strands

Element	Residues	Length	Sheet
β-strand	432	1	11
β-strand	435-436	2	1
β-strand	445-450	6	5
β-strand	461-467	7	5
β-strand	472-475	4	5
α-helix	477-480	4
β-strand	481	1	12
β-strand	491	1	12
α-helix	492-493	2
α-helix	494-496	3
β-strand	498-501	4	5
β-strand	515-522	8	5
β-strand	536-540	5	5
α-helix	543-546	4
β-strand	547	1	13
β-strand	550	1	13
β-strand	554	1	1
α-helix	563-564	2
β-strand	568-573	6	1
β-strand	599-606	8	1
α-helix	607	1
α-helix	608-617	10
β-strand	620	1	4
β-strand	628-631	4	1
β-strand	639	1	11
β-strand	648-653	6	1
β-strand	658-668	11	1
β-strand	680-684	5	1
α-helix	685-687	3
α-helix	689-695	7

Chain F: 11 helices, 22 β-strands

Element	Residues	Length	Sheet
β-strand	432	1	14
β-strand	436	1	7
β-strand	445-451	7	10
β-strand	460-467	8	10
β-strand	472-475	4	10
α-helix	478-480	3
β-strand	481	1	15
β-strand	491	1	15
α-helix	492-493	2
α-helix	494-496	3
β-strand	497-500	4	10
β-strand	515	1	10
β-strand	519-522	4	10
β-strand	527	1	16
β-strand	532	1	16
β-strand	536-539	4	10
β-strand	554	1	7
α-helix	555-556	2
α-helix	564	1
β-strand	568-573	6	7
β-strand	599-606	8	7
α-helix	607	1
α-helix	608-614	7
β-strand	620	1	9
β-strand	628-631	4	7
β-strand	639	1	14
α-helix	647	1
β-strand	648-653	6	7
β-strand	658-668	11	7
α-helix	679	1
β-strand	680-684	5	7
α-helix	685-687	3
α-helix	689-696	8

Molecules and chains

Molecule	Chains	Type	Length	Organism	UniProt
Ecotin	C, D	protein	142	Escherichia coli	P23827 (AlphaFold model)
Mannan-binding lectin serine protease 3	E, F	protein	279	Homo sapiens	P48740 (AlphaFold model)

Sequence of entity 1 (C, D), FASTA

>4IW4_1 Ecotin (chains C, D)
AESVQPLEKIAPYPQAEKGMKRQVIQLTPQEDESTLKVELLIGQTLEVDCNLHRLGGKLE
NKTLEGWGYDYYVFDKVSSPVSTMMACPDGKKEKKFVTAYLGDAGMLRYNSKLPIVVYTP
DNVDVKYRVWKAEEKIDNAVVR

Sequence of entity 2 (E, F), FASTA

>4IW4_2 Mannan-binding lectin serine protease 3 (chains E, F)
IIGGRNAEPGLFPWQALIVVEDTSRVPNDKWFGSGALLSASWILTAAHVLRSQRRDTTVI
PVSKEHVTVYLGLHDVRDKSGAVNSSAARVVLHPDFNIQNYNHDIALVQLQEPVPLGPHV
MPVCLPRLEPEGPAPHMLGLVAGWGISNPNVTVDEIISSGTRTLSDVLQYVKLPVVPHAE
CKTSYESRSGNYSVTENMFCAGYYEGGKDTCLGDSGGAFVIFDDLSQRWVVQGLVSWGGP
EECGSKQVYGVYTKVSNYVDWVWEQMGLPQSVVEPQVER

Primary citation

The Serine Protease Domain of MASP-3: Enzymatic Properties and Crystal Structure in Complex with Ecotin. Gaboriaud, C., Gupta, R.K., Martin, L. et al. PLoS One (2013) 8:e67962-e67962. DOI 10.1371/journal.pone.0067962 · PubMed

Other PDB entries of the same protein (UniProt P23827 (AlphaFold model), which also has an AlphaFold model), best resolution first:

1SLU 1.8 Å, Rat anionic N143H, E151H trypsin complexed to A86H ecotin
1IFG 2.0 Å, Crystal structure of a monomeric form of general protease inhibitor, ecotin in absence…
1N8O 2.0 Å, Crystal structure of a complex between bovine chymotrypsin and ecotin
1SLW 2.0 Å, Rat anionic N143H, E151H trypsin complexed to A86H ecotin; nickel-bound
1ECY 2.19 Å, Protease inhibitor ecotin
1FI8 2.2 Å, Rat granzyme B [N66Q] complexed to ecotin [81-84 iepd]
1SLX 2.2 Å, Rat anionic N143H, E151H trypsin complexed to A86H ecotin; zinc-bound
1XX9 2.2 Å, Crystal Structure of the FXIa Catalytic Domain in Complex with EcotinM84R
1AZZ 2.3 Å, Fiddler crab collagenase complexed to ecotin
1EZS 2.3 Å, Crystal structure of ecotin mutant M84R, W67A, G68A, Y69A, D70A bound to rat anionic…
1SLV 2.3 Å, Rat anionic N143H, E151H trypsin complexed to A86H ecotin; copper-bound
1EZU 2.4 Å, Ecotin Y69F, D70P bound to D102N trypsin

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