A primitive enzyme for a primitive cell: the protease required for excystation of giardia

Article Abstract:

The effect of a specific cysteine enzyme protease inhibitor on excystation of Giardia was analyzed by incubation of Giardia muris fecal cysts with peptidyl fluoromethyl ketone morpholine-tyrosine (o-methyl)homophenylalanine fluoromethyl ketone (Mu-Tyr(Ome)-hPhe-FMK) at 7-100uM. Excystation was arrested by the cysteine protease inhibitor E-64. However, the enzyme reportedly has no effect on trophozoite motility and replication. Furthermore, enzyme protease activity was localized in cytoplasmic vacuoles by using fluorescent microscopy.

author: Alvarado, Lilia, Engel, Juan C., Franklin, Christopher, McKerrow, James H., Rawlings, Neil D., Ward, Wendy
Development and progression, Genetic aspects, Pathogenic microorganisms, Microbial mutation, Gene amplification, Protozoa, Protozoans, Protozoa, Pathogenic

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CDK-independent activation of estrogen receptor by cyclin D1

Article Abstract:

Cyclin D1 acts as a cyclin-dependent kinases (CDK)-independent activator of the estrogen receptor. This novel role for cyclin D1 in growth regulation of estrogen-responsive tissues is carried out by potentiating transcription of estrogen receptor-regulated genes. Cyclin D1 is observed to mediate this activation independent of complex formation to a CDK partner and activates estrogen receptor-mediated transcription in the absence of estrogen and enhances transcription in its presence. This activation is not inhibited by anti-estrogens.

author: Bernards, Rene, Zwijsen, Renate M.L., Wientjens, Ellen, Klompmaker, Rob, Sman, Jeroen van der, Michalides, Rob J.A.M.
Analysis, Cell cycle, Protein kinases, Estrogen, Estrogen receptors

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The adenovirus protease is activated by a virus-coded disulphide-linked peptide

Article Abstract:

The mechanism of activation of adenovirus protease was investigated. Protease activity could be reconstituted by the presence of a factor from purified virions. Characterization of the isolated factor indicated that it is a 11 amino acid peptide derived from the C-terminus of the structural protein, pVI (pVI-CT). The mechanism of activation involves a thiol-disulphide exchange which is associated with the cysteine residue in pVI-CT.

author: Webster, Ailsa, Hay, Ronald T., Kemp, Graham
Adenoviruses

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subjects list: Research, Proteases, Enzyme activation
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