Each of the activities of signal recognition particle (SRP) is contained within a distinct domain: analysis of biochemical mutants of SRP |
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Authors: | V Siegel P Walter |
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Affiliation: | Department of Biochemistry and Biophysics, University of California, San Francisco 94143-0448. |
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Abstract: | 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. |
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