### A. Overview

Extracellular purines (adenosine, ADP, and ATP) and pyrimidines (UDP and UTP) are important signaling molecules that mediate diverse biological effects via cell-surface receptors termed purine receptors. In this review particular emphasis is placed on the discrepancy between the

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Receptors for Purines and Pyrimidines

The small (40S) subunit of eukaryotic ribosomes is believed to bind initially at the capped 5'-end of messenger RNA and then migrate, stopping at the first AUG codon in a favorable context for initiating translation. The first-AUG rule is not absolute, but there are rules for breaking the rule. Some anomalous observations that seemed to contradict the scanning mechanism now appear to be artifacts. A few genuine anomalies remain unexplained.

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The scanning model for translation: an update.

GTPases are conserved molecular switches, built according to a common structural design. Rapidly accruing knowledge of individual GTPases--crystal structures, biochemical properties, or results of molecular genetic experiments--support and generate hypotheses relating structure to function in other members of the diverse family of GTPases.

The GTPase superfamily: conserved structure and molecular mechanism

The protective effects of estrogen on the cardiovascular system

Mechanical forces associated with blood flow play important roles in the acute control of vascular tone, the regulation of arterial structure and remodeling, and the localization of atherosclerotic lesions. Major regulation of the blood vessel responses occurs by the action of hemodynamic shear stresses on the endothelium. The transmission of hemodynamic forces throughout the endothelium and the mechanotransduction mechanisms that lead to biophysical, biochemical, and gene regulatory responses of endothelial cells to hemodynamic shear stresses are reviewed.

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Flow-mediated endothelial mechanotransduction

Networking ionic channels by G proteins.

STRUCTURAL AND FUNCTIONAL PROPERTIES OF NS AND Ni, THE REGULATORY COMPONENTS OF ADENYLYL CYCLASES*

CHAPTER 12 – Receptor–Effector Coupling by Pertussis Toxin Substrates: Studies with Recombinant and Native G-Protein α Subunits

Publisher Summary This chapter discusses procedure for the purification of Gs and Gi (mixture of Gi2 and Gi3) from human erythrocytes, followed by an example of separate purification of Gi2 from Gi3. A general protocol for activation and isolation of the activated α subunits of the three G proteins is given. The activation and isolation procedure are applied for α subunits to purified Gi1 and G0 proteins as well. The procedures for G-protein purification avoid the use of stabilizing ligands such as NaF/Mg and nonhydrolyzable GTP analogs [e.g., guanylyl imidodiphosphate (GMP-P(NH)P) or GTPγS] which are known to affect functionally the behavior and activity of G proteins. While eliminating many possible alterations of the subunit composition of these proteins as might result from the effect of these ligands to induce subunit dissociation. The γ subunits of Gs and Gi comigrate on urea and polyacrylamide gel electrophoresis with an apparent Mr of about 5000, and using two-dimensional peptide mapping they appear to be the same for Gs and a pool of Gi2 plus Gi3.

Juan Codina

Papers

Networking ionic channels by G proteins.

STRUCTURAL AND FUNCTIONAL PROPERTIES OF NS AND Ni, THE REGULATORY COMPONENTS OF ADENYLYL CYCLASES*

CHAPTER 12 – Receptor–Effector Coupling by Pertussis Toxin Substrates: Studies with Recombinant and Native G-Protein α Subunits

)Preparation of activated alpha subunits of Gs and Gis: from erythrocyte to activated subunit.

Gating of atrial muscarinic K+ channels by G proteins.