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Figure symbols: 147 3D models

The simple icons research figures use: Pac-Man enzymes and lock-and-key substrates, receptors and ligands, antibodies, drugs as pills or little balls, channels and pumps, phosphate beads, ROS, electrons, hν and Δ, activation arrows and inhibition T-bars (real sizes any). Each one is a ready-made 3D model you can turn, recolour and place in a figure — open BioDioRama and type its name in the Library search.

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Figure symbols · Arrows & annotations · Figure symbols · Enzymes & catalysis · Figure symbols · Receptors, ligands & antibodies · Figure symbols · Drugs & small molecules · Figure symbols · Membranes, channels & transporters · Figure symbols · Ions, electrons & reactive species · Figure symbols · Signalling & modifications · Figure symbols · Nucleic acids & genes · Figure symbols · Carriers, microbes & cell states

Figure symbols · Arrows & annotations 18

Activation arrow (→) — The universal "activates / leads to" arrow of signalling and mechanism figures. Dashed = indirect or proposed.
Inhibition T-bar (⊣) — A line ending in a flat bar: "inhibits / blocks". Usually red.
Catalysis connector (circle head) — A line ending in an open circle — "catalyses" in SBGN pathway diagrams.
Double-headed arrow (⇄ crosstalk) — Two-way exchange or crosstalk between two processes.
Equilibrium arrows (⇌) — Two half-headed arrows pointing opposite ways: a reversible reaction at equilibrium.
Curved process arrow — A curved arrow arching over a reaction step, often carrying a cofactor in or out (ATP → ADP).
Cycle arrows (feedback loop) — Arrows chasing each other round a ring: a cycle, recycling or a feedback loop.
Up-regulation arrow (↑) — A short bold upward arrow next to a label: increased, up-regulated.
Down-regulation arrow (↓) — A short bold downward arrow: decreased, down-regulated.
Red cross (× blocked) — A bold red × over a pathway, protein or cell: blocked, absent, prevented.
Green check mark (✓) — A green tick: working, restored, successful.
Starburst (activation / stress badge) — A spiky burst used as an "activated", "stress" or "damage" badge.
Lightning bolt (stimulus / injury) — A yellow zig-zag bolt for an external stimulus, electrical shock, injury or ischaemia.
Stop sign — A red octagon: halt, termination, stop codon.
Question mark bubble (unknown mechanism) — A speech bubble with "?" for an unknown or unproven step.
Plus badge (+) — A round "+" token: positive, added, increased.
Minus badge (−) — A round "−" token: negative, removed, decreased.
Balance (homeostasis / imbalance) — A tilted beam on a pivot: the balance between two sides (oxidants vs antioxidants, Th17 vs Treg).

Figure symbols · Enzymes & catalysis 18

Pac-Man enzyme — The near-universal cartoon enzyme: a ball with a wedge-shaped mouth. Colour encodes the enzyme class in the figure legend.
Pac-Man enzyme degrading a chain — An enzyme cutting a bead chain (protein or nucleic acid) into pieces.
Lock-and-key enzyme and substrate — An enzyme block with a shaped active site and the substrate that exactly fits it. Pick the shape of the fit in the settings.
Enzyme–substrate complex — The substrate sitting in the active site, with a glow for the reaction happening.
Induced fit (open → closed) — The same enzyme twice: open, then closed around its substrate — the induced-fit model.
Substrate → products — A substrate shape split into two product halves leaving the enzyme.
Competitive inhibitor in the active site — A look-alike that fits the active site but is wrong at one edge, so the real substrate cannot bind.
Allosteric (non-competitive) inhibitor — An inhibitor bound at a second site distorts the active site so the substrate no longer fits.
Allosteric activator — A small activator at a side pocket opens the active site.
Cofactor / coenzyme (NAD⁺, FAD) — A small disc labelled as a cofactor, docked beside the enzyme.
Metal ion in an active site — A single glossy metal ion (Zn²⁺, Mg²⁺, Fe) cradled in the enzyme pocket.
Protease scissors cutting a chain — Scissors at the cleavage site of a bead chain — protease or nuclease cutting.
Kinase adding a phosphate (P) — A kinase passes a phosphate "P" bead onto its target protein — phosphorylation.
Phosphatase removing a phosphate — A phosphatase pulls the "P" bead off a protein — dephosphorylation.
Proteasome — A barrel of stacked rings with caps: ubiquitin-tagged proteins go in, short peptides come out.
Degraded protein fragments — A protein broken into jagged pieces — degraded.
ATP energy token — A small badge for ATP (energy in), often shown as ATP → ADP + Pᵢ.
Multi-enzyme cascade — Three enzymes in a row passing a substrate along a pathway.

Figure symbols · Receptors, ligands & antibodies 12

Generic receptor with its ligand — A receptor through the membrane with a shaped binding cup on top and the ligand that fits it.
Receptor tyrosine kinase (Y-shaped dimer) — Two receptor stalks splayed into a Y, with intracellular kinase boxes — an RTK dimer.
GPCR (seven-transmembrane receptor) with G protein — A receptor snaking seven times through the membrane, with the Gα/β/γ trio below.
Nuclear receptor on DNA — A receptor protein with its ligand sitting on a DNA double helix — a ligand-activated transcription factor.
Receptor antagonist (blocker) — An angular red blocker capping the receptor so the real ligand cannot bind.
Activated receptor (signal glow) — A ligand-bound receptor with a glow at its tail inside the cell: signalling switched on.
Antibody (IgG) — The Y of four capsule segments: two heavy chains (stem and inner arms) and two light chains (outer arms).
Bispecific antibody — A Y whose two arms bind two different targets — the arms in two colours.
Antibody fragment / nanobody — A single small antibody arm (Fab, scFv or a camelid nanobody).
Antibody–drug conjugate (ADC) — An antibody carrying small drug balls on linkers.
IgM pentamer — Five antibody Ys joined at their stems in a star — the first antibody made in an immune response.
Aptamer (folded nucleic acid) — A single strand folded into a stem-loop that binds its target.

Figure symbols · Drugs & small molecules 12

Drug (two-tone capsule) — The universal drug / therapy symbol of pathway figures: a two-colour capsule.
Drug (round tablet) — A round scored tablet.
Drug molecules (small coloured balls) — Drug molecules drawn as a scatter of small glossy balls — how most figures show a drug entering a cell or loaded in a carrier.
Small molecule (simplified ball-and-stick) — Five or six coloured balls on sticks — a generic small molecule.
Drug (single hexagon / benzene ring) — One bright hexagon standing for a drug molecule.
Syringe / injection — A syringe with coloured liquid: injection, vaccine, intravenous dose.
IV bag — An infusion bag with its line.
Drug vial — A small vial with a coloured cap.
PROTAC / bifunctional degrader — Two different ligand shapes joined by a linker: one grabs the target, the other recruits an E3 ligase.
Prodrug with a masking group — A drug ball wearing a cap that pops off at its target (enzyme, pH or light trigger).
Natural product (leaf + molecule) — A leaf beside a small molecule — a compound from plants.
Toxin / poison — A purple spiky ball — a toxin; or the skull-and-crossbones for poison.

Figure symbols · Membranes, channels & transporters 16

Lipid bilayer — Two rows of lipid heads with their tails meeting in the middle — the cell membrane.
Phospholipid — One lipid: a round polar head with two wavy fatty-acid tails.
Ion channel (open) — Four subunits round a central pore, open so ions flow through.
Ion channel (closed) — The same channel shut: its gate closed, ions held outside.
Ligand-gated channel — A channel that opens when its ligand (e.g. a neurotransmitter) binds at the top.
Voltage-gated channel (+/−) — A channel with "+ + +" outside and "− − −" inside: opened by a change in membrane voltage.
Transporter (carrier, rocking) — A two-lobed carrier open to one side of the membrane, cargo in its central pocket.
Na⁺/K⁺-ATPase pump — A pump using ATP to push 3 Na⁺ out and bring 2 K⁺ in.
Symporter / antiporter — A transporter moving two cargoes: same direction (symport) or opposite (antiport).
Efflux pump (drug resistance) — A tube spanning the bacterial envelope pumping a drug ball out of the cell.
Porin (β-barrel) — An open barrel through the outer membrane letting small molecules pass.
Aquaporin with water — A water channel with water molecules filing through.
Endocytosis (budding vesicle) — The membrane folding in round cargo and pinching off as a vesicle.
Exocytosis (vesicle releasing cargo) — A vesicle fused with the membrane, spilling its dots outside — secretion or neurotransmitter release.
Gap junction — Paired channels joining two neighbouring cell membranes.
Lipid raft with cholesterol — Rigid yellow cholesterol rods packed among the lipids.

Figure symbols · Ions, electrons & reactive species 26

Ca²⁺ ion dots — Calcium ions as small labelled dots (Ca²⁺).
Na⁺ ion dots — Sodium ions as small labelled dots (Na⁺).
K⁺ ion dots — Potassium ions as small labelled dots (K⁺).
Cl⁻ ion dots — Chloride ions as small labelled dots (Cl⁻).
H⁺ ion dots — Proton ions as small labelled dots (H⁺).
Mg²⁺ ion dots — Magnesium ions as small labelled dots (Mg²⁺).
Zn²⁺ ion dots — Zinc ions as small labelled dots (Zn²⁺).
Fe²⁺ ion dots — Iron ions as small labelled dots (Fe²⁺).
Electron (e⁻) — A small sphere labelled e⁻ with a motion trail — electron transfer.
Hole (h⁺) — An open circle labelled h⁺ — the missing electron left in a semiconductor band.
ROS (reactive oxygen species) stars — Red spiky stars scattered round a cell — oxidative stress.
Hydroxyl radical (•OH) — A radical with its unpaired-electron dot: •OH (also O₂•⁻, ¹O₂ in chemistry figures).
Band diagram (VB / CB, photocatalysis) — Two bands with an electron excited across the gap by light, leaving a hole behind.
Light (hν wavy arrow) — A wavy arrow labelled hν — light or irradiation.
Laser / NIR beam — A red beam cone with a wavy line — NIR laser for photothermal therapy.
Heat (Δ / flame) — Red wavy heat lines rising from a flame — heating, Δ.
Cold (snowflake) — A snowflake for cooling or freezing.
Reaction arrow with catalyst — A reaction arrow with "cat." (or a catalyst sphere) above it.
Catalyst nanoparticle on a support — A metal nanoparticle sitting on a support slab, with molecules adsorbing on it.
Single-atom catalyst site — One bright metal atom held in a hexagonal carbon (graphene) sheet.
Electrode / battery symbol — A plate with + and − ends, or a battery with a lightning sign.
Energy diagram (activation energy) — An energy curve with a hump (Eₐ) and a lower, catalysed hump.
Ultrasound waves — Concentric arcs from a transducer — ultrasound or sonodynamic therapy.
Magnet and field lines — A red/blue horseshoe magnet with field lines — magnetic targeting or MRI.
Radiation (trefoil) — The radiation trefoil — radiotherapy, X-rays or a radioisotope.
Gas bubbles — Clear bubbles rising — gas evolution.

Figure symbols · Signalling & modifications 9

Signalling cascade (protein blobs) — Rounded protein blobs, one colour per step, linked by activation arrows.
Phosphate (P) bead — A small yellow circled "P" on a stalk — a phosphorylated residue.
Ubiquitin chain — A string of small "Ub" spheres tagging a protein for degradation.
Histone tail with Ac / Me marks — A histone tail with acetyl (Ac) and methyl (Me) flags — epigenetic marks.
Second messenger (cAMP) — A small hexagon labelled cAMP (or IP₃, DAG).
Transcription factor moving to DNA — An oval factor sitting on DNA, with an arrow into the nucleus.
Cytokines released from a cell — Tiny coloured ovals streaming from a cell — cytokine secretion.
Hormone in a blood vessel — A small hexagonal hormone travelling down a vessel.
Protein complex (scaffold) — Several protein blobs docked together on a scaffold.

Figure symbols · Nucleic acids & genes 16

DNA double helix (icon) — Two twisted ribbons with coloured rungs — the stylised DNA of figures.
mRNA (cap and poly-A tail) — A single wavy strand with a 5′ cap ball and a poly(A) tail.
siRNA duplex — A short straight double rod in two colours — siRNA.
Plasmid with a gene — A circle of DNA with a coloured gene arc and a promoter arrow.
Gene with promoter arrow — A horizontal line with coloured exon boxes and a bent promoter arrow.
Cas9 with guide RNA (CRISPR) — A large lobed Cas9 clamping a guide-RNA hairpin on DNA, with scissors at the cut.
Chromosome (X-shape) — Two sister chromatids joined at the centromere.
Nucleosome — DNA wrapped 1.7 turns around a histone disc.
Ribosome translating mRNA — Large and small subunits on an mRNA with a bead-chain peptide emerging.
Peptide (bead chain) — A string of coloured beads — a peptide or protein chain.
Glycan symbol: GlcNAc — GlcNAc in the Symbol Nomenclature for Glycans (SNFG) — the standard colour and shape for drawing glycans.
Glycan symbol: Man — Man in the Symbol Nomenclature for Glycans (SNFG) — the standard colour and shape for drawing glycans.
Glycan symbol: Gal — Gal in the Symbol Nomenclature for Glycans (SNFG) — the standard colour and shape for drawing glycans.
Glycan symbol: Fuc — Fuc in the Symbol Nomenclature for Glycans (SNFG) — the standard colour and shape for drawing glycans.
Glycan symbol: Neu5Ac (sialic acid) — Neu5Ac (sialic acid) in the Symbol Nomenclature for Glycans (SNFG) — the standard colour and shape for drawing glycans.
Glycan symbol: Glc — Glc in the Symbol Nomenclature for Glycans (SNFG) — the standard colour and shape for drawing glycans.

Figure symbols · Carriers, microbes & cell states 20

Liposome with drug (icon) — A hollow bilayer sphere with drug dots in its watery core.
Micelle (icon) — Heads outward, tails inward, drug in the oily core.
PEGylated nanoparticle (icon) — A glossy core with a fuzzy purple PEG brush.
Targeted nanoparticle (with ligands) — A nanoparticle decorated with targeting antibodies or peptides on stalks.
Virus (spiked) — A sphere with evenly spaced spikes — the coronavirus-style icon.
Bacteriophage (icon) — Icosahedral head, tail tube and splayed legs.
Bacterium (rod with flagellum) — A capsule-shaped bacillus with a curly flagellum.
Cocci (cluster and chain) — A grape-like cluster (staphylococci) beside a bead chain (streptococci).
Yeast (budding) — An oval cell with a small bud.
Biofilm — Bacteria embedded in a translucent dome of matrix on a surface.
Healthy cell — A smooth round cell with its nucleus.
Apoptotic cell (blebbing) — A shrunken cell with surface blebs, a broken-up nucleus and budding apoptotic bodies.
Necrotic / pyroptotic cell (ruptured) — A swollen cell with a torn membrane spilling its contents.
Cell proliferation (dividing cell) — A cell pinching into two daughters — proliferation.
Senescent cell — A flattened, enlarged, grey cell.
Inflamed cell — A red cell with a flame badge — inflammation.
Migrating cell (motion lines) — A cell with motion lines and an arrow — migration, invasion.
Macrophage engulfing particles — A large irregular cell reaching round particles with pseudopods.
T cell with receptors — A round blue cell bristling with small TCR stalks.
Mitochondrion (icon) — The bean with folded cristae — energy, metabolism, ROS.