Each of the activities of signal recognition particle (SRP) is contained within a distinct domain: analysis of biochemical mutants of SRP.
Signal recognition particle (SRP), a small ribonucleoprotein required for targeting secretory proteins to the ER, has three known functions: signal recognition, elongation arrest, and translocation promotion. Because SRP is inactivated by the sulfhydryl alkylating reagent N-ethylmaleimide (NEM), we have attempted to establish structure-function relationships within SRP by assembling particles in which a single protein is modified. Alkylation of the 68/72 kd protein of SRP yields a particle that arrests elongation but fails to promote translocation and no longer interacts with SRP receptor. Alkylation of the 54 kd protein yields a particle that fails to recognize signal sequences. This approach has allowed us to map activities to specific protein domains on SRP, and should be generally useful for analyzing other ribonucleoproteins.
Siegel
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Department of Biochemistry and Biophysics, University of California, San Francisco 94143-0448.
Walter
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D000818:Animals; D002499:Centrifugation, Density Gradient; D002846:Chromatography, Affinity; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D005033:Ethylmaleimide / Q000494:pharmacology; D007425:Intracellular Membranes / Q000378:metabolism; D008861:Microsomes / Q000378:metabolism; D009154:Mutation; D010641:Phenotype; D011388:Prolactin / Q000096:biosynthesis / Q000235:genetics; D014176:Protein Biosynthesis; D011498:Protein Precursors / Q000096:biosynthesis / Q000235:genetics; D021382:Protein Sorting Signals / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018160:Receptors, Cytoplasmic and Nuclear; D018000:Receptors, Peptide; D012261:Ribonucleoproteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D018271:Signal Recognition Particle
D011498:Protein Precursors; D021382:Protein Sorting Signals; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; D018000:Receptors, Peptide; D012261:Ribonucleoproteins; D018271:Signal Recognition Particle; C036318:signal peptide receptor; C017671:preprolactin; D011388:Prolactin; D005033:Ethylmaleimide