Enzyme Substrates

CD45 (Ser 940) is a pivotal enzyme involved in the regulation of immune cell signaling. Its phosphorylation at Ser 940 modulates its phosphatase activity, influencing T-cell receptor signaling pathways. This modification alters the enzyme's conformation, enhancing its interaction with specific substrates and affecting reaction kinetics. CD45's role in dephosphorylating key signaling molecules is essential for maintaining cellular communication and modulating immune responses.

Cdc6 (Ser 54) is a crucial enzyme in the initiation of DNA replication, playing a key role in the assembly of the pre-replicative complex. Phosphorylation at Ser 54 influences its binding affinity to other replication factors, thereby regulating the timing of DNA synthesis. This modification affects the enzyme's stability and interaction with the origin recognition complex, ultimately impacting the efficiency of DNA replication and ensuring genomic integrity during cell division.

Cdc6 (Ser 106) is an essential enzyme involved in the regulation of DNA replication. Its phosphorylation at Ser 106 modulates its interaction with the origin recognition complex, enhancing the recruitment of additional replication factors. This post-translational modification influences the enzyme's conformational dynamics, affecting its stability and activity. By fine-tuning these interactions, Cdc6 (Ser 106) ensures precise control over the initiation phase of DNA replication, contributing to cellular proliferation and genomic stability.

Cdc25C (Ser 216) is a pivotal phosphatase that plays a crucial role in cell cycle regulation, particularly during the G2/M transition. The phosphorylation at Ser 216 enhances its catalytic activity, promoting the dephosphorylation of cyclin-dependent kinases (CDKs). This action accelerates the activation of CDK1, facilitating mitotic entry. Cdc25C's interactions with regulatory proteins and its involvement in feedback loops underscore its significance in maintaining cell cycle fidelity and timing.

Connexin 43 (mSer 262) is a key gap junction protein that facilitates intercellular communication through the formation of channels between adjacent cells. Phosphorylation at Ser 262 modulates its channel conductance and gating properties, influencing the permeability to ions and small molecules. This dynamic regulation is crucial for maintaining tissue homeostasis and coordinating cellular responses. Its interactions with cytoskeletal elements and signaling pathways further highlight its role in cellular connectivity and function.

Elk-1 (Ser 383) is a transcription factor that plays a pivotal role in cellular signaling pathways, particularly in response to growth factors. Phosphorylation at Ser 383 enhances its transcriptional activity, promoting the expression of target genes involved in cell proliferation and differentiation. This modification influences Elk-1's interaction with other transcriptional co-activators and chromatin remodeling complexes, thereby modulating gene expression dynamics and cellular responses to environmental stimuli.

ERα (Ser 104/106) is a key player in estrogen signaling, acting as a transcription factor that regulates gene expression in response to hormonal stimuli. Phosphorylation at these serine residues alters its conformation, enhancing its affinity for co-regulators and influencing chromatin accessibility. This modification fine-tunes the receptor's interaction with DNA, impacting downstream signaling pathways and cellular processes such as growth and metabolism, while also affecting its stability and degradation.

FADD (Ser 194) is a crucial adaptor protein involved in apoptotic signaling pathways. Phosphorylation at this serine residue modulates its interaction with death receptors, enhancing the recruitment of caspases and promoting the formation of the death-inducing signaling complex (DISC). This modification influences the kinetics of apoptosis, facilitating rapid cellular responses to stress signals. Additionally, FADD's structural dynamics play a role in its ability to integrate multiple signaling cascades, impacting cell fate decisions.

FAK (Ser 722) is a pivotal enzyme that plays a significant role in cellular signaling and adhesion processes. Phosphorylation at this serine residue enhances its interaction with various integrins, promoting focal adhesion formation. This modification influences downstream signaling pathways, particularly those related to cell migration and survival. The enzyme's unique structural conformation allows it to act as a scaffold, integrating signals from multiple sources and modulating cellular responses to environmental cues.

IPP-1 (Ser 67) is an enzyme characterized by its unique catalytic mechanism, which involves the formation of a transient enzyme-substrate complex. This interaction facilitates the transfer of phosphate groups, significantly influencing metabolic pathways. Its kinetic properties reveal a high affinity for specific substrates, allowing for rapid turnover rates. Additionally, IPP-1 exhibits allosteric regulation, enabling it to respond dynamically to cellular energy levels and modulate enzymatic activity accordingly.