serine129

Serine129 (often abbreviated Ser129) denotes the serine amino acid residue in a protein sequence at position 129. The designation is used across proteins, and the actual residue depends on the protein's length and sequence; different species and isoforms can shift numbering. Serine residues are common targets for phosphorylation, a reversible post-translational modification that can alter a protein's activity, interactions, stability, or localization. In many contexts, Ser129 participates in regulatory signaling cascades through kinase-mediated phosphorylation, where various kinases may target the motif.

A well-studied example is the serine at position 129 in alpha-synuclein, a small neuronal protein implicated in synaptic function. Phosphorylation at Ser129 is markedly enriched in aggregated, insoluble alpha-synuclein found in Lewy bodies, which are characteristic of Parkinson's disease and other synucleinopathies. The functional consequences of Ser129 phosphorylation in alpha-synuclein remain under investigation: some studies report that phosphorylation modulates aggregation or clearance, while others suggest it is a byproduct of pathology rather than a driving factor. It is also considered a potential biomarker for disease progression in certain contexts.

Other proteins with a serine at position 129 may have serine-specific regulation, but Ser129 does not have a universal function beyond the context of its protein. In general, residues at such positions are considered in structural analyses to assess phosphorylation sites and their impacts on protein structure.