Translocation of proteins across the endoplasmic reticulum. I. Signal recognition protein (SRP) binds to in-vitro-assembled polysomes synthesizing secretory protein
نویسندگان
چکیده
An 11S protein composed of six polypeptide chains was previously purified from a salt extract of dog pancreas microsomal membranes and shown to be required for translocation of nascent secretory protein across the microsomal membrane (Wistar and Blobel 1980 Proc. Natl. Acad. Sci. U. S. A. 77:7112-7116). This 11S protein, termed signal recognition protein (SRP), has been shown here (a) to inhibit translation in the wheat germ cell-free system selectively of mRNA for secretory protein (bovine preprolactin) but not of mRNA for cytoplasmic protein (alpha and beta chain of rabbit globin); (b) to bind with relatively low affinity (apparent KD less than 5 x 10(-5)) to monomeric wheat germ ribosomes; and (c) to bind selectively and with 6,000-fold higher affinity (apparent KD less than 8 x 10(-9)) to wheat germ ribosomes engaged in the synthesis of secretory protein but not to those engaged in the synthesis of cytoplasmic protein. Low- and high-affinity binding as well as the selective translation-inhibitory effect were abolished after modification of SRP by N-ethyl maleimide. High-affinity binding and the selective translation-inhibitory effect of SRP were largely abolished when the leucine (Leu) analogue beta-hydroxy leucine was incorporated into the nascent secretory polypeptide.
منابع مشابه
Translocation of proteins across the endoplasmic reticulum.
Translocation-competent microsomal membrane vesicles of dog pancreas were shown to selectively bind nascent, in vitro assembled polysomes synthesizing secretory protein (bovine prolactin) but not those synthesizing cytoplasmic protein (alpha and beta chain of rabbit globin) . This selective polysome binding capacity was abolished when the microsomal vesicles were salt-extracted but was restored...
متن کاملTranslocation of proteins across the endoplasmic reticulum. II. Signal recognition protein (SRP) mediates the selective binding to microsomal membranes of in-vitro-assembled polysomes synthesizing secretory protein
متن کامل
Translocation of proteins across the endoplasmic reticulum. II. Signal recognition protein (SRP) mediates the selective binding to microsomal membranes of in-vitro-assembled polysomes synthesizing secretory protein
Translocation-competent microsomal membrane vesicles of dog pancreas were shown to selectively bind nascent, in vitro assembled polysomes synthesizing secretory protein (bovine prolactin) but not those synthesizing cytoplasmic protein (alpha and beta chain of rabbit globin). This selective polysome binding capacity was abolished when the microsomal vesicles were salt-extracted but was restored ...
متن کاملTranslocation of Proteins Across the Endoplasmic Reticulum
Translocation-competent microsomal membrane vesicles of dog pancreas were shown to selectively bind nascent, in vitro assembled polysomes synthesizing secretory protein (bovine prolactin) but not those synthesizing cytoplasmic protein (alpha and beta chain of rabbit globin) . This selective polysome binding capacity was abolished when the microsomal vesicles were salt-extracted but was restored...
متن کاملCharacterization of secretory protein translocation: ribosome-membrane interaction in endoplasmic reticulum
Secretory proteins are synthesized on ribosomes bound to the membrane of the endoplasmic reticulum (ER). After the selection of polysomes synthesizing secretory proteins and their direction to the membrane of the ER via signal recognition particle (SRP) and docking protein respectively, the polysomes become bound to the ER membrane via an unknown, protein-mediated mechanism. To identify protein...
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عنوان ژورنال:
- The Journal of Cell Biology
دوره 91 شماره
صفحات -
تاریخ انتشار 1981