Protein: CO4A
Complement C4-A (Acidic complement C4) (C3 and PZP-like alpha-2-macroglobulin domain-containing protein 2) [Cleaved into: Complement C4 beta chain; Complement C4-A alpha chain; C4a anaphylatoxin; Complement C4b-A (Complement C4b-alpha' chain); Complement C4d-A; Complement C4 gamma chain]

Gene: CO4A, C4A
Organism: Homo sapiens
Interactions: 97
UniProt ID: P0C0L4

Gene Ontology (top 5):
GO:0001849 - complement component C1q complex binding
GO:0004866 - endopeptidase inhibitor activity
GO:0005576 - extracellular region
GO:0005615 - extracellular space
GO:0005788 - endoplasmic reticulum lumen

Download interactions: TXT   MITAB-2.5

Interaction Interactor Experiments Homologs Category Interaction
Score
Confidence

125803

MASP2
Mannan-binding lectin serine protease 2

4

8

Small-scale

0.882

High

262199

SCN2B
Sodium channel regulatory subunit beta-2

3

4

High-throughput

0.861

High

501798

PVR
Poliovirus receptor

2

1

High-throughput

0.811

High

444675

CO2
Complement C2

2

20

Small-scale

0.778

High

501832

VSIG1
V-set and immunoglobulin domain-containing protein 1

2

1

High-throughput

0.726

High

132987

MATN2
Matrilin-2

1

3

High-throughput

0.691

High

486867

C1S
Complement C1s subcomponent

1

7

Small-scale

0.691

High

501823

CD226
CD226 antigen

1

3

High-throughput

0.691

High

127257

LEG8
Galectin-8

3

7

High-throughput

0.667

High

501797

CCL5
C-C motif chemokine 5

2

2

High-throughput

0.628

High

369816

CO3
Complement C3

1

4

High-throughput

0.618

High

501805

MASP1
Mannan-binding lectin serine protease 1

1

7

Small-scale

0.618

High

501842

FHR4
Complement factor H-related protein 4

1

20

Small-scale

0.618

High

501850

PINK1
Serine/threonine-protein kinase PINK1, mitochondrial

2

4

High-throughput

0.611

High

501837

GDPD1
Lysophospholipase D GDPD1

3

2

High-throughput

0.609

High

501796

LAMP1
Lysosome-associated membrane glycoprotein 1

2

0

High-throughput

0.602

High

501803

S15A1
Solute carrier family 15 member 1

2

0

High-throughput

0.602

High

501813

AT2B2
Plasma membrane calcium-transporting ATPase 2

2

0

High-throughput

0.602

High

501826

OCLN
Occludin

2

0

High-throughput

0.602

High

501829

F171B
Protein FAM171B

2

0

High-throughput

0.602

High

501859

PILRA
Paired immunoglobulin-like type 2 receptor alpha

1

0

Small-scale

0.586

High

501848

SNX27
Sorting nexin-27

2

2

High-throughput

0.574

High

370999

MYC
Myc proto-oncogene protein

2

3

High-throughput

0.571

High

501801

APC
Adenomatous polyposis coli protein

1

2

High-throughput

0.541

High

194455

P2RX6
P2X purinoceptor 6

1

4

High-throughput

0.536

High

254760

HCN1
Potassium/sodium hyperpolarization-activated cyclic nucleotide-gated channel 1

1

3

High-throughput

0.536

High

351651

SG1D1
Secretoglobin family 1D member 1

1

4

High-throughput

0.536

High

421370

A4
Amyloid-beta precursor protein

1

4

High-throughput

0.536

High

501799

AATC
Aspartate aminotransferase, cytoplasmic

1

3

High-throughput

0.536

High

501807

STX17
Syntaxin-17

1

4

High-throughput

0.536

High

501812

IL5RA
Interleukin-5 receptor subunit alpha

1

1

High-throughput

0.536

High

501831

MTA70
N(6)-adenosine-methyltransferase catalytic subunit METTL3

1

1

High-throughput

0.536

High

501835

NRSN1
Neurensin-1

1

3

High-throughput

0.536

High

501845

SIA7F
Alpha-N-acetylgalactosaminide alpha-2,6-sialyltransferase 6

1

4

High-throughput

0.536

High

501849

ECSIT
Evolutionarily conserved signaling intermediate in Toll pathway, mitochondrial

1

1

High-throughput

0.536

High

389938

ALBU
Albumin

1

0

High-throughput

0.513

High

465830

MSMB
Beta-microseminoprotein

1

0

High-throughput

0.513

High

501802

INGR2
Interferon gamma receptor 2

1

0

High-throughput

0.513

High

461060

HS90A
Heat shock protein HSP 90-alpha

1

2

Small-scale

0.501

High

501800

HXB6
Homeobox protein Hox-B6

1

3

High-throughput

0.489

High

501810

HXA4
Homeobox protein Hox-A4

1

3

High-throughput

0.489

High

501811

HXC5
Homeobox protein Hox-C5

1

4

High-throughput

0.489

High

501836

RYBP
RING1 and YY1-binding protein

1

5

High-throughput

0.489

High

501844

PIGT
GPI-anchor transamidase component PIGT

1

3

High-throughput

0.489

High

501846

SARAF
Store-operated calcium entry-associated regulatory factor

1

3

High-throughput

0.489

High

501856

MET14
N(6)-adenosine-methyltransferase non-catalytic subunit METTL14

1

1

High-throughput

0.489

High

501861

SSUH2
Protein SSUH2 homolog

1

4

High-throughput

0.489

High

370031

CYTC
Cystatin-C

1

0

Small-scale

0.480

High

217747

TGON2
Trans-Golgi network integral membrane protein 2

1

2

High-throughput

0.479

High

388944

FINC
Fibronectin

1

5

Small-scale

0.479

High

400170

RAF1
RAF proto-oncogene serine/threonine-protein kinase

1

3

High-throughput

0.479

High

501838

NHLC2
NHL repeat-containing protein 2

1

2

High-throughput

0.479

High

501854

TRI31
E3 ubiquitin-protein ligase TRIM31

1

3

High-throughput

0.479

High

128734

MEN1
Menin

1

0

High-throughput

0.458

High

459201

CATL1
Procathepsin L

1

0

Small-scale

0.458

High

261065

NSMA
Sphingomyelin phosphodiesterase 2

1

2

High-throughput

0.445

High

388485

CRP

1

1

High-throughput

0.445

High

501809

LCN6
Epididymal-specific lipocalin-6

1

3

High-throughput

0.445

High

501814

C1QBP
Complement component 1 Q subcomponent-binding protein, mitochondrial

1

2

Small-scale

0.445

High

501819

CAC1C
Voltage-dependent L-type calcium channel subunit alpha-1C

1

1

High-throughput

0.445

High

501824

ADIPO
Adiponectin

1

1

High-throughput

0.445

High

501841

CA054
Uncharacterized protein C1orf54

1

1

High-throughput

0.445

High

501860

ITM2B
Integral membrane protein 2B

1

5

High-throughput

0.445

High

105181

APRIO
Alternative prion protein

1

2

High-throughput

0.437

High

413058

P53
Cellular tumor antigen p53

1

1

High-throughput

0.437

High

501804

SOX2
Transcription factor SOX-2

1

4

High-throughput

0.437

High

501808

UBE2H
Ubiquitin-conjugating enzyme E2 H

1

2

High-throughput

0.437

High

501815

EP300
Histone acetyltransferase p300

1

1

High-throughput

0.437

High

501816

FOXO1
Forkhead box protein O1

1

7

High-throughput

0.437

High

501817

FOXC1
Forkhead box protein C1

1

7

High-throughput

0.437

High

501821

KIF22
Kinesin-like protein KIF22

1

1

High-throughput

0.437

High

501827

OTU1
Ubiquitin thioesterase OTU1

1

1

High-throughput

0.437

High

501834

ASXL1
Polycomb group protein ASXL1

1

3

High-throughput

0.437

High

501839

FBX22
F-box only protein 22

1

1

High-throughput

0.437

High

501840

DOT1L
Histone-lysine N-methyltransferase, H3 lysine-79 specific

1

1

High-throughput

0.437

High

501843

TF3B
Transcription factor IIIB 90 kDa subunit

1

1

Small-scale

0.437

High

501851

FACD2
Fanconi anemia group D2 protein

1

6

High-throughput

0.437

High

501853

HOIL1
RanBP-type and C3HC4-type zinc finger-containing protein 1

1

2

Small-scale

0.437

High

501855

ASXL3
Putative Polycomb group protein ASXL3

1

5

High-throughput

0.437

High

501857

RNF12
E3 ubiquitin-protein ligase RLIM

1

7

High-throughput

0.437

High

501858

ZRAN1
Ubiquitin thioesterase ZRANB1

1

5

High-throughput

0.437

High

501818

DNJC3
DnaJ homolog subfamily C member 3

1

0

High-throughput

0.426

High

501820

RFTN1
Raftlin

1

0

High-throughput

0.426

High

501830

BRID5
BRICHOS domain-containing protein 5

1

0

High-throughput

0.426

High

501833

TMM25
Transmembrane protein 25

1

0

High-throughput

0.426

High

501852

TX101
Testis-expressed protein 101

1

0

High-throughput

0.426

High

213047

CP110
Centriolar coiled-coil protein of 110 kDa

1

1

High-throughput

0.407

High

501828

CP135
Centrosomal protein of 135 kDa

1

2

High-throughput

0.407

High

60862

TMM89
Transmembrane protein 89

3

0

High-throughput

0.342

High

501822

FL2D
Pre-mRNA-splicing regulator WTAP

1

0

High-throughput

0.279

Low

135034

IF2B3
Insulin-like growth factor 2 mRNA-binding protein 3

1

0

High-throughput

0.249

Low

319331

UFL1
E3 UFM1-protein ligase 1

1

0

High-throughput

0.249

Low

501806

MCM2
DNA replication licensing factor MCM2

1

0

High-throughput

0.249

Low

501825

TAF9
Transcription initiation factor TFIID subunit 9

1

0

High-throughput

0.249

Low

501847

DDRGK
DDRGK domain-containing protein 1

1

0

High-throughput

0.249

Low

501863

UBP15
Ubiquitin carboxyl-terminal hydrolase 15

1

0

Small-scale

0.249

Low

501862

NF2L3
Nuclear factor erythroid 2-related factor 3

1

0

High-throughput

0.232

Low


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Last updated: 11Aug2025