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High‐Protein Carboxymethylase Activity and Low Endogenous Methyl Acceptor Proteins in Posterior Pituitary Lobe of Rats Lacking Neurophysin‐Vasopressin (Brattleboro Rats)
Author(s) -
Saavedra Juan M.,
Kloog Yoel,
Chevillard Claude,
FernandezPardal Julio
Publication year - 1983
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1983.tb13669.x
Subject(s) - posterior pituitary , neurophysins , diabetes insipidus , medicine , endocrinology , vasopressin , methylation , endogeny , pituitary gland , biology , chemistry , biochemistry , hormone , gene
Abstract: The activity of protein carboxymethylase and the endogenous protein methyl acceptor capacity were examined in the posterior, intermediate, and anterior lobes of the pituitaries of homozygous Brattleboro rats with diabetes insipidus and in heterozygous Brattleboro and Long‐Evans control rats. Protein carboxyl methylation is selectively altered in the posterior pituitary lobes of homozygous Brattleboro rats. Protein carboxymethylase activity is higher (+40%) and endogenous methyl acceptor protein capacity is lower (‐80%) with respect to heterozygous Brattleboro and Long‐Evans control rats. This latter change is correlated with decreased methylation of proteins of a molecular weight of approximately 11K daltons, is selective for the posterior pituitary lobe, since it does not occur in the intermediate and anterior lobes, and probably reflects the absence of vasopressin‐associated neurophysin in homozygous Brattleboro rats. Our results support a physiological role of protein carboxyl methylation in the neurosecretory process in the posterior pituitary gland.