A recurring organization of protein secondary structure elements in three dimensions. Structural-cluster counts depend on comparison criteria and should not automatically be equated to counts of distinct topological folds.

A segment of a protein that does not maintain one stable folded structure under the specified conditions. An otherwise folded protein can contain such a region, so a region should not be equated with an entire intrinsically disordered protein.

A Ramachandran plot displays backbone $\varphi ,\psi$ angles. glycine has a broader sterically allowed region because its side chain is hydrogen, whereas proline ring closure strongly restricts $\varphi$.

Detection of proteins with Coomassie dyes, commonly after electrophoresis. Binding produces visible bands whose intensity can support comparison under controlled conditions, with background and saturation limiting quantification.

An altered or isolated component interferes with the activity of its normal counterpart, for example by sequestering a limiting partner into a nonproductive protein complex.

A protein-protein interaction network represents proteins as nodes and recorded interactions as edges. Direct physical binding, membership of a larger complex and functional association are different edge meanings and should be distinguished. A highly connected node can reflect biology, experimental sampling or both. The network is useful for proposing coordinated functions, but an edge alone does not identify binding affinity, direction of signalling or simultaneous occupancy. ^[ref]

Reversible biomolecular association with a relatively high dissociation constant under specified conditions. The same equilibrium constant can result from different association and dissociation rates, so weak binding does not alone establish a short lifetime.

The possession of several interaction sites in one molecule or assembly. Multiple contacts can give avidity, crosslinking or collective assembly, depending on geometry and partner concentrations.

Protein oligomerization associates several protein subunits into a defined assembly, such as a protein dimer. It can create cooperative binding sites, regulate activity or build structural units. A measured assembly depends on concentration and conditions: a dimer can dissociate on dilution. Determining subunit count therefore requires an assay model as well as a measured size or signal. ^[ref]

Association between molecules of the same protein. Such contacts can create cooperative assemblies or bridges; visible clustering alone does not establish phase separation.

A phosphatase promoting reversal of mitotic CDK phosphorylation and exit from mitosis in budding yeast.

A family of metal-dependent phosphatases. Selected clade-A members inhibit ABA signaling; this role should not be generalized to every member of the family.

A protein kinase whose substrates include regulatory proteins involved in cell migration and local biological translation.

A stress-responsive protein kinase linking amino acid starvation and starved-ribosome signals to eIF2 phosphorylation.

A protein kinase regulated downstream of mTORC1, linking nutrient signaling to growth and translational control.

A kinase activated and regulated through association with a cyclin. Changing activity helps impose the order of replication, mitosis and mitotic exit.

A kinase involved in mitotic chromosome-attachment error correction and later coordination of cytokinesis, including responses to chromatin bridges.

A kinase complex that promotes eukaryotic replication initiation through phosphorylation of the MCM complex and related regulatory events.

A kinase participating in eukaryotic responses to replication stress and certain DNA lesions, including signalling to Chk1.

A checkpoint kinase that helps couple DNA replication stress and damage responses to cell-cycle progression.