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Anti‐(p34 protein) antibodies inhibit ribosome binding to and protein translocation across the rough microsomal membrane
Author(s) -
Ichimura Tohru,
Shindo Yukiko,
Uda Yasuyo,
Ohsumi Tomoya,
Omata Saburo,
Sugano Hiroshi
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)81799-6
Subject(s) - ribosome , microsome , membrane protein , biochemistry , chromosomal translocation , integral membrane protein , chemistry , translocon , protein biosynthesis , antibody , membrane , biology , microbiology and biotechnology , in vitro , rna , gene , immunology
The p34 protein is a non‐glycosylated, integral membrane protein characteristic of rough microsomes and is believed to play a role in the ribosome‐membrane association. Here, antibodies directed against p34 were examined as to their inhibitory effect on ribosome binding to and protein translocation across the microsomal membrane. Preincubation of the stripped (ribosome‐depleted) membrane with anti‐p34 immunoglobulins (IgGs) or their Fab fragments led to more than 80% inhibition of the binding of ribosomes and their large (60S) subunit to the membrane. The inhibition was dependent on the amount of antibodies used, but comparable amounts of IgGs and Fab fragments from nonimmune serum had less effect. The p34 antibodies were also inhibitory for cotranslational translocation of secretory proteins, i.e. placental lactogen and serum albumin, across the membrane. These results suggest that p34 is involved in the binding of ribosomes to the microsomal membrane and that it is in close proximity to the protein translocation site in the microsomal membrane.