Open AccessPurification and characterization of subforms of the guanine‐nucleotide‐binding proteins Gα i and Gα o
Author(s) -
LANG Jochen
Publication year - 1989
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1111/j.1432-1033.1989.tb21099.x
Subject(s) - g protein , alpha (finance) , pertussis toxin , gtp binding protein regulators , microbiology and biotechnology , guanine , g alpha subunit , gel electrophoresis , fibroblast activation protein, alpha , biochemistry , biology , proteases , chemistry , nucleotide , receptor , protein subunit , enzyme , gene , medicine , construct validity , genetics , nursing , cancer , patient satisfaction
Five different pertussis‐toxin‐sensitive guanine‐nucleotide‐binding proteins (G proteins) were purified from bovine brain. Immunochemical characterization of α subunits identified two Gα o proteins (Gα o ‐I and Gα o ‐II), two 41‐kDa Gα i proteins (Gα i ‐I and Gα i ‐II) and the 40‐kDa Gα i2 protein. Site‐directed antisera specific for Gα o proteins did not differentiate between Gα o ‐I and Gα o ‐II. However, in situ peptide mapping using polyacrylamide gel electrophoresis revealed distinct cleavage products with different proteases for each of these proteins. Additionally comparison of R f values demonstrated a slightly faster migration for Gα o ‐II than for Gα o ‐I, which is the only type of Gα o protein present in cell membranes of the neuroblastoma/glioma cell line NG 108–15. The importance of these structural differences and possible functional implications are discussed.