HSP101 functions as a specific translational regulatory protein whose activity is regulated by nutrient status

Article Abstract:

HSP101, a tobacco mosaic virus (TMV) 102-kD protein homologous to the HSP101/HSP104/ClpB heat shock protein family, acts as a specific translation-regulation protein. Its activity is controlled by nutrient status. RNA-binding and translation regulatory activites of HSP101 are not active in respiring cells or in those subject to limits on nutrients, but thermotolerance functions of the protein are unaffected in those circumstances. A protein necessary for specific translation enhancement of capped mRNAs has never been identified before nor has a translation-regulation function for a heat shock protein been reported. No functional distinction between the two eIF4G proteins found in eukaryotes has been made before. HSP101 binds the 68-nucleotide 5' leader which is partly responsible for efficient translation of TMV mRNA. The leader has no guanosine residues and has a central poly(CAA) region needed for stimulation of translation.

User Contributions:

Comment about this article or add new information about this topic:

Comment:  (50-4000 characters)

Name:

E-mail:

Security Code:

The HIV-1 Tat cellular coactivator Tat-SF1 is a general transcription elongation factor

Article Abstract:

Tat-Sf1, an HIV-1 Tat cellular coactivator protein, is a transcription elongation factor of the general sort. It stimulates transcription elongation from the HIV-1 long terminal repeat (LTR) strongly and specifically. It provides a very useful in vitro model system to study the process. Protein-affinity chromatography has been used to identify cellular factors with important roles in transcription elongation. Results indicate that an ATP-inactivatable general elongation factor (AIEF) necessary for Tat-SF1 activity, and for which Tat can substitute in a functional way, exists.

User Contributions:

Comment about this article or add new information about this topic:

Comment:  (50-4000 characters)

Name:

E-mail:

Security Code:

Eph signaling is required for segmentation and differentiation of the somites

Article Abstract:

Segmentation of the paraxial mesoderm into parts lined up on the anteroposterior axis is an aspect of somitogenesis. Eph and ephrin are factors in signaling for patterning of presomitic mesoderm as well as in formating of somites. The role of certain proteins has been studied. Dominant negative forms of Eph receptors and ephrins were encoded. Eph signaling is essential for differentiation and segmentation of the somites.

User Contributions:

Comment about this article or add new information about this topic:

Comment:  (50-4000 characters)

Name:

E-mail:

Security Code: