SRP—Where the RNA and Membrane Worlds Meet

摘要

Life is thought to have originated in an RNA world where RNA molecules were responsible for both catalysis and information storage. Historic records of ancient RNA machines are found in the conserved inner workings of today's ri-bonucleoprotein complexes. In all cells these structures of RNA and protein— which include spliceosomes, ribosomes, and the signal recognition particle (SRP)—mediate essential steps in the processing of genetic information encoded in the DNA and its translation into protein. To perform their myriad tasks, newly synthesized proteins have to be directed to the correct location—to the cell cytoplasm, the plasma membrane, or an extracellular destination. It is the job of the SRP to select proteins destined to be secreted or integrated into the plasma membrane and to target them to the endoplasmic reticulum in eukaryotic cells (or to the plasma membrane in prokaryotic cells).