Intercellular Localization of Acid Invertase in Tomato Fruit and Molecular Cloning of a cDNA for the Enzyme

Abstract

The localization of acid invertase (AI, EC 3.2.1.26) in tomato fruits was studied. AI was localized in the intercellular fraction (cell wall fraction). A cDNA encoding a wall-bound form of AI from tomato fruits was cloned and its nucleotide sequence was determined. The cloned cDNA was 2363 base pairs long and contained an open reading frame of 1908 base pairs which encoded a polypeptide of 636 amino acids. RNA blot analysis indicated that the mRNA for the acid invertase was about 2.5 kb in length. The levels of the mRNA were low at the mature green stage but increased during ripening of fruit.