Signal recognition particle (SRP) -- a particle composed of proteins and 7SL RNA that binds to signal sequences and targets polypeptide chains to the endoplasmic reticulum.

• 讯息（指挥）序列--蛋白质末端的一段疏水性氨基酸，在细菌中引导蛋白质分泌或在真核细胞中将蛋白质并入内质网。