We have compared the melanogenic activities of cultured melanocytes carrying two common TYR alleles as homozygous 192S-402R wild-type, heterozygous and homozygous variant. This includes assays of TYR protein, DOPAoxidase activity, glycosylation and temperature sensitivity of protein and DOPAoxidase levels. Homozygous wild-type strains on average had higher levels of TYR protein and enzyme activ...

Tyrosol (Tyr) is a natural phenolic antioxidant with diverse biological activities. We compared the anti-inflammatory effects of intravenously administered Tyr versus prednisolone (PSL) in an endotoxin-induced uveitis (EIU) rat model. Intravenous administration of 100 mg/kg Tyr was performed 2 hr before, simultaneously and 2 hr after lipopolysaccharide (LPS) injection. Tyr treatment was associa...

The catalytic and signaling activities of RET, a receptor-type tyrosine kinase, are regulated by the autophosphorylation of several tyrosine residues in the cytoplasmic region of RET. Some studies have revealed a few possible autophosphorylation sites of RET by [(32)P]phosphopeptide mapping or by using specific anti-phosphotyrosine antibodies. To ultimately identify these and other autophosphor...

Phosphorylated residues occur preferentially in the intrinsically disordered regions of eukaryotic proteins. In the disordered amino-terminal region of human α-actinin-4 (ACTN4), Tyr(4) and Tyr(31) are phosphorylated in cells stimulated with epidermal growth factor (EGF), and a mutant with phosphorylation-mimicking mutations of both tyrosines exhibits reduced interaction with actin in vitro. Cl...

Protein tyrosine (Tyr) phosphorylation plays a central role in many signaling pathways leading to cell growth and differentiation in animals. Tyr phosphorylated proteins have been detected in higher plants, and the roles of protein Tyr phosphatases and protein Tyr kinases in some physiological responses have been shown. We investigated the involvement of Tyr phosphorylation events in abscisic a...

We report herein anti-proliferation effects of 4-arylthiosemicarbazides, with a cyclopentane substitution at N1 position, on highly virulent RH strain Toxoplasma gondii. Among them, the highest in vitro anti-Toxoplasma activity was found meta-iodo derivative. Further experiments demonstrated inhibitory thiosemicarbazides tyrosinase (Tyr) activity, and good correlation between percentage Tyr inh...

Studies with lactoperoxidase showed that a highly reactive intermediate is produced (on the enzyme) from I- and H2O2 which then diffuses from the enzyme and very rapidly and indiscriminately iodinates any Tyr or peptides containing Tyr which are in the same solution. The evidence supporting these conclusions follows. 1) The rate followed the Michaelis-Menten pattern with I- and H2O2 while the c...

We found previously that restriction of tyrosine (Tyr) and phenylalanine (Phe) inhibited growth and metastasis of B16BL6 murine melanoma and arrested these cells in the G0-G1 phase of the cell cycle. Here, we report that deprivation of these two amino acids in vitro induces apoptosis in B16BL6 and in human A375 melanoma cells but not in nontransformed, neonatal murine epidermal cells or human i...

The reversible labeling of tyrosine (Tyr)-containing peptide, which involves detection and recovery, is described in this paper. The phenolic-OH in Tyr structure reacted with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) under a mild condition at room temperature in alkaline medium. The resulting derivative absorbed at around 280 nm and 380 nm. However, the fluorescence was very weak. The NBD m...