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Synthesis of lens protein in vitro VI. Methionyl‐tRNA from eye lens
Author(s) -
Strous G.,
Van Westreenen J.,
Bloemendal H.
Publication year - 1971
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(71)80599-9
Subject(s) - library science , citation , genetics , biology , computer science
Methionyl-tRNAF has been isolated from bacteria [l] mitochondria [2] and chloroplasts [3]. This tRNA species initiates polypeptide chains in prokaryotic cells [4]. In eukaryotes evidence is accumulating that methionyl-tRNA is involved in the initiation of perhaps all cytoplasmic proteins [S, 61 in spite of suggestions that N-acetyl-valine [7], Nacetyl-glycine [8] and N-acetyl-serine [9] play the role of initiators of protein biosynthesis. A blocked cysteinyl-tRNA which accumulates on rabbit reticulocyte ribosomes after NaF treatment has also recently been reported [lo]. In relatively short nascent peptide chains of e.g. hemoglobin methionine has been detected in the NH2 -terminal position [ 111. However, in the mature protein methionine is removed enzymatically, presumably already in an early stage of peptide chain growth. It has been stressed earlier that the eye lens is a most useful tool for the study of cell differentiation at the molecular level, as the process of differentiation occurs during the whole life span of the lens [ 121 . We described the properties of the lens cell-free system previously [ 13161. Structural studies of the major lens protein, (Ycrystallin, revealed that acetylated methionine occurs in the NHa-terminal position [ 17, 181. In connection with this striking feature a search was made for initiator tRNA in lens tissue. This paper describes the isolation of three met-tRNA’s from calf eye lens.