I2B is a small cytosolic protein that participates in vacuole fusion

AUTOR(ES)

Slusarewicz, Paul

FONTE

The National Academy of Sciences of the USA

RESUMO

Saccharomyces cerevisiae vacuole inheritance requires two low molecular weight activities, LMA1 and LMA2. LMA1 is a heterodimer of thioredoxin and protease B inhibitor 2 (I2B). Here we show that the second low molecular weight activity (LMA2) is monomeric I2B. Though LMA2/I2B was initially identified as a protease B inhibitor, this protease inhibitor activity is not related to its ability to promote vacuole fusion: (i) Low Mr protease B inhibitors cannot substitute for LMA1 or LMA 2, (ii) LMA1 and LMA2 promote the fusion of vacuoles from a strain that has no protease B, (iii) low concentrations of LMA2 that fully inhibit protease B do not promote vacuole fusion, and (iv) LMA1, in which I2B is complexed with thioredoxin, is far more active than LMA2/I2B in promoting vacuole fusion and far less active in inhibiting protease B. These studies establish a new function for I2B.

Documentos Relacionados

• Vacuole Fusion Regulated by Protein Phosphatase 2C in Fission Yeast
• Protein Cryoprotective Activity of a Cytosolic Small Heat Shock Protein That Accumulates Constitutively in Chestnut Stems and Is Up-Regulated by Low and High Temperatures1
• Cytosolic Delivery and Characterization of the TcdB Glucosylating Domain by Using a Heterologous Protein Fusion
• A Sm-like protein complex that participates in mRNA degradation
• Altered I-A protein-mediated transmembrane signaling in B cells that express truncated I-Ak protein.