The elongation factor 1 A-2 isoform from rabbit: cloning of the cDNA and characterization of the protein.
Eukaryotic elongation factor 1 A (eEF1A, formerly elongation factor-1 alpha) is an important component of the protein synthesis apparatus. Here we report the isolation and characterization of the cDNA sequence encoding rabbit eEF1A-2, an isoform of eEF1A, as well as a structural and functional comparison of the two rabbit isoforms. Northern analysis of the expression pattern of eEF1A-2 showed that this isoform is expressed in skeletal muscle, heart, brain and aorta, while transcripts are not detected in liver, kidney, spleen and lung. In contrast, the previously characterized eEF1A-1 isoform is expressed in all tissues examined except skeletal muscle. We have recently purified eEF1A-2 from rabbit skeletal muscle. By partial amino acid sequencing and determination of the post-translational modifications of eEF1A-2 we found that both of the glycerylphosphorylethanolamine modifications observed in eEF1A-1 appear to be present in eEF1A-2. However, two of the residues found dimethylated in eEF1A-1 appeared to be trimethylated in eEF1A-2. A comparison of the enzymatic activity showed that eEF1A-1 and eEF1A-2 have indistinguishable activity in an in vitro translation system. In contrast, the GDP dissociation rate constant is approximately 7 times higher for eEF1A-1 than for eEF1A-2. The nucleotide preference ratio (GDP/GTP) for eEF1A-1 was 0.82, while the preference ratio for eEF1A-2 was 1.50.
Kahns
S
S
Division of Biostructural Chemistry, IMSB, Aarhus University, Gustav Wieds vej 10C, 8000 Arhus C, Denmark.
Lund
A
A
Kristensen
P
P
Knudsen
C R
CR
Clark
B F
BF
Cavallius
J
J
Merrick
W C
WC
D000595:Amino Acid Sequence; D000818:Animals; D001011:Aorta / Q000378:metabolism; D001921:Brain / Q000378:metabolism; D003001:Cloning, Molecular; D018076:DNA, Complementary; D020963:GTP Phosphohydrolase-Linked Elongation Factors / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D015723:Gene Library; D007700:Kinetics; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism; D020648:Peptide Elongation Factor 1; D010445:Peptide Elongation Factors / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011817:Rabbits; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
D018076:DNA, Complementary; D020648:Peptide Elongation Factor 1; D010445:Peptide Elongation Factors; D011994:Recombinant Proteins; D020963:GTP Phosphohydrolase-Linked Elongation Factors