Lupus La protein

Lupus La protein (SSB) is a 408-amino acid RNA-binding protein that protects nascent RNA polymerase III transcripts from exonuclease digestion, facilitating their folding and maturation (UniProt: P05455). The protein also functions in viral translation, binding the internal ribosome entry site of Coxsackievirus B3 to enhance IRES-mediated translation.

SSB is primarily involved in RNA quality control and processing pathways across tissues where transcription occurs. UniProt records no direct disease associations in its curated entries.

In Alzheimer's Disease, SSB shows increased abundance in post-mortem AD brain tissue compared to age-matched controls, with a mean log2 fold-change of 0.65 (Chaparral AD proteomics). This up-regulation was detected in one of four subcellular fractions analyzed via TMT-labeled tandem mass spectrometry, suggesting a potential role in AD-related RNA metabolism or neuronal stress responses, though the functional significance of this elevation remains to be established.