The signal recognition particle (SRP) is a ribonucleoprotein complex essential for co-translational targeting of secretory and membrane proteins to the endoplasmic reticulum. SRP14. a 14 kDa protein, is one of six polypeptides in the SRP complex, forming a heterodimer with SRP9 to stabilize the Alu domain critical for translational arrest. Antibodies targeting SRP14 are primarily associated with autoimmune disorders, notably immune-mediated necrotizing myopathy (IMNM), a subtype of idiopathic inflammatory myopathy. These autoantibodies are detected in approximately 4-6% of myositis patients and correlate with severe, progressive muscle weakness, elevated creatine kinase levels, and poor response to conventional immunosuppressive therapies.
SRP14 antibodies are part of the anti-SRP autoantibody spectrum, which recognizes multiple SRP components. Their pathogenic role remains unclear but may involve disrupting SRP function, impairing protein translocation, or triggering complement-mediated muscle fiber damage. Diagnosis relies on immunoassays (e.g., ELISA, immunoprecipitation) confirming reactivity against the SRP complex. Clinically, anti-SRP positivity aids in classifying IMNM and guiding aggressive treatment, often combining corticosteroids, intravenous immunoglobulins, and rituximab. Research continues to explore epitope specificity and molecular mechanisms linking SRP14 autoimmunity to muscle pathology.