Overview of proteins relevant for Medical Biochemistry
| Protein | Function | Involved in disease or pathway |
|---|---|---|
| APAF-1 | Forms a pro-apoptotic complex with cytochrome c called the apoptosome | Apoptosis, intrinsic pathway |
| BAD, BAX, BAK | Pro-apoptotic proteins | Apoptosis, intrinsic pathway |
| Bcl-2 | Anti-apoptotic protein | Anti-apoptosis |
| Caspases | Cascade that activates apoptosis | Apoptosis |
| Caspase-dependent DNase (CAD) | Cleaves DNA, activated by caspases | Apoptosis |
| Cathepsins | Proteases, degrade proteins | Involved in autophagy |
| DIABLO, AIF, EndoG, cytochrome c | Pro-apoptotic proteins released from mitochondria | Apoptosis, intrinsic pathway |
| RIPK1, RIPK3 | Form a complex called necrosome | Necroptosis |
| Protein | Function | Involved in disease or pathway |
|---|---|---|
| ATM, ATR | Activated by MRN, activates p53 | Cell cycle regulation |
| CDK | Regulates cell cycle together with cyclin | Cell cycle regulation |
| Cyclin | Regulates cell cycle together with CDK | Cell cycle regulation |
| DBRP | Recognizes destruction box, causes degradation of cyclin | Cell cycle regulation |
| E2F | Transcription factor | Cell cycle |
| Jun, Fos | Transcription factors | Cell cycle regulation |
| MRN | Detects double-stranded DNA damage, activates ATM and ATR | DNA damage detection |
| Protein | Function | Involved in disease or pathway |
|---|---|---|
| Actin (F-actin) | Component of microfilaments | |
| Agrin | Formation of neuromuscular junction | |
| Arp2/3 complex | Control branching of actin | |
| Cadherin | Cell adhesion | Cell adhesion |
| Desmin | Component of intermediate filaments in myocytes | |
| Elastin | Component of elastic fibers | |
| Fibrillin | Component of microfibrils | |
| Flippases | Move lipids to the inner leaflet | Cell membrane homeostasis |
| Floppases | Move lipids to the outer leaflet. Belongs to the ABC transporter family. | Cell membrane homeostasis |
| Formin | Activates polymerization of actin | |
| GFAP | Component of intermediate filaments in glial cells | |
| Integrins | Adhesion molecules binding cells to ECM | Cell adhesion |
| Keratin type I and II | Component of intermediate filaments in epithelial cells | |
| Kinesins, dyneins | Motor proteins that travel on microtubules | |
| Laminin | Component of basal lamina | Component of basal lamina |
| Lamin | Component of intermediate filaments in nucleus | Charcot-Marie-Tooth syndrome |
| MMP2, MMP9 | Cleave gelatin and collagen type IV | Matrix metalloproteases |
| MMP3 | Activates other MMPs | Matrix metalloproteases |
| Neurexin, neuroligin | Adhesion molecules found in synaptic cleft | Cell adhesion |
| Neurofilaments | Component of intermediate filaments in neurons | |
| Periferin | Component of intermediate filaments in neurons | |
| Plasmin | Activates MMP3 | Matrix metalloproteases |
| Rac | Activates WAVE and cortactin | |
| Tau | Stabilizes microtubules in nervous system | Taupathies, Alzheimer’s, Parkinson’s |
| TIMPs | Inhibit MMPs | Matrix metalloproteases |
| Type I collagen | Found in scar tissue | |
| Type IV collagen | Found in basal lamina | |
| Type XI collagen | Found in cartilage | |
| Vimentin | Component of intermediate filaments in every cell at the beginning of differentiation | |
| WASP, WAVE, cortactin | Activates Arp2/3 complex |
| Protein | Function | Involved in disease or pathway |
|---|---|---|
| Aquaporin 2 | Water transporter in the kidney, activated by PKA in response to AVP | Water reabsorption |
| CFTR | Chloride ion channel. Member of ABC transporter family. | Cystic fibrosis |
| GLUT5 | Fructose transporter in enterocyte | Dietary fructose absorption |
| HbA1c | Hemoglobin with glucose attached to β-chain. Correlates with long-term blood glucose average | Laboratory analysis |
| Perilipin | A protein that covers lipid droplets in adipose tissue which prevents enzymes from degrading the lipids. | Lipolysis |
| PEX5, PEX7 | Peroxisome surface receptor, recognized PTS1 and PTS2 | Protein transport to the peroxisomes |
| SGLT1 | Glucose and galactose transporter in enterocyte | Dietary glucose and galactose absorption |
| SGLT2 | Glucose transporter in kidney | Glucose reabsorption |
| Protein | Function | Involved in disease or pathway |
|---|---|---|
| APP (amyloid precursor protein) | Precursor of amyloid plaques | Alzheimer’s, amyloidosis |
| α-Synuclein | Precursor of Lewy bodies | Parkinson’s, others |
| DJ-1 | Inhibits proteasome when mutated | Parkinson’s |
| Frataxin | Formation of iron-sulphur clusters | Friedreich’s ataxia |
| Huntingtin | Causes Huntington’s when its gene contains too many CAG sequences | Huntington’s |
| LRRK2 | Disrupts mitochondria when mutated | Parkinson’s |
| Parkin | Inhibits proteasome when mutated | Parkinson’s |
| PINK-1 | Disrupts mitochondria when mutated | Parkinson’s |
| PrP | Prion disease precursor in human | Prion disease |
| Tau | Stabilizes microtubules in nervous system | Taupathies, Alzheimer’s, Parkinson’s |
| Protein | Function | Involved in disease or pathway |
|---|---|---|
| Ask1 | Activates MAPK pathway in response to oxidative stress | Response against oxidative stress |
| Fyn | Inhibits Nrf2 during chronic oxidative stress | Response against oxidative stress |
| IKKβ | Activates NF-κB in response to oxidative stress | Response against oxidative stress |
| IRE1, PERK, ATF6 | Detect accumulation of misfolded proteins in ER | Unfolded protein response |
| Keap1 | Inhibits Nrf2 | Response against oxidative stress |
| Nrf2 | Transcription factor for anti-oxidant processes. | Response against oxidative stress |
| SIRT1, SIRT2, SIRT3 | Decrease ROS production, other beneficial functions, activates FOXO | Response against oxidative stress |
| XBP1, PERK, CHOP | Activates by accumulation of misfolded proteins in ER. Activate BAD | Unfolded protein response |
Plasma proteins
| Protein | Function | Involved in disease or pathway |
|---|---|---|
| Albumin | Transport molecule, buffering, maintaining oncotic pressure | |
| α1-antitrypsin | Inhibit neutrophil proteases | |
| α1-fetoprotein (AFP) | Fetal form of albumin | |
| Ceruloplasmin | Copper transport in blood, ROS removal | |
| C-reactive protein | Opsonizes bacteria, activates complement system | Immune system |
| Haptoglobin | Binds free hemoglobin in blood | Hemoglobin recirculation |
| Transferrin | Iron transport in blood |
Rheumatoid arthritis
| Protein | Function | Involved in disease or pathway |
|---|---|---|
| Anti-CCP | Antibodies against citrullinated proteins | Rheumatoid arthritis |
| PAD | Citrullinates arginine-residues on proteins. | Rheumatoid arthritis |
| Rheumatoid factor | Autoantibody, targets Fc region of IgG | Rheumatoid arthritis |
Transcription factors
| Protein | Function | Involved in disease or pathway |
|---|---|---|
| FOXO | Inactivated by PKB and activated by SIRT1, activates transcription of G6Pase and PEPCK | |
| mTOR | Activated by PKB, activates protein synthesis | |
| Nrf2 | Transcription factor for anti-oxidant processes. | Response against oxidative stress |
Tumor suppressors and proto-oncogenes
| Protein | Function | Involved in disease or pathway |
|---|---|---|
| ErbB | EGF receptor | Cancer, proto-oncogene |
| p16 | Involved in senescence. | Tumor suppressor, senescence |
| p21 (cip) | CDK-cyclin heterodimer inhibitor | Tumor suppressor, senescence |
| p27 (kip) | CDK-cyclin heterodimer inhibitor | Tumor suppressor |
| p53 | Transcription factor, increases transcription of p21 | Tumor suppressor, senescence |
| PTEN | Reverses the action of PI3K, so it inhibits PDK1 and therefore PKB. | Tumor suppressor |
| Rab | GLUT4 translocation to cell membrane | Cancer, proto-oncogene |
| Ran | Transport in and out of nucleus | Cancer, proto-oncogene |
| Ras | Insulin-mediated cell proliferation | Cancer, proto-oncogene |
| Retinoblastoma protein (pRb) | Inhibit E2F when double-stranded DNA damage is present | Tumor suppressor |
| Rho | Cell cycle | Cancer, proto-oncogene |