Calculation of a Gap restoration in the membrane skeleton of the red blood cell: possible role for myosin II in local repair.

Human red blood cells contain all of the elements involved in the formation of nonmuscle actomyosin II complexes (V. M. Fowler.

Cl- -HCO3- exchange in developing neonatal rat cardiac cells. Biochemical identification and immunolocalization of band 3-like proteins.

The Cl- -HCO3- exchanger is the main anionic exchanger (AE) that alleviates alkaline loads in cardiac cells. We recently identified in adult ventricular cells two membrane proteins (80 and 120 kD) immunologically related to the erythroid band 3 and likely to mediate the anion exchange. In the present study, we further investigated the Cl- -HCO3- exchanger activity concomitantly with the expression and intracellular localization of the band 3-like proteins during the development of neonatal rat cardiac cells maintained in culture for 17 days.

Tubulin is not phosphorylated in resting and thrombin-activated platelets.

We have investigated tubulin phosphorylation in human platelets, in order to evaluate whether it might be involved in the microtubular marginal band reorganization during platelet activation. Tubulin was identified with the use of specific monoclonal antibodies directed against alpha and beta subunits of tubulin. After metabolic 32P-labeling of platelets and analysis of separated proteins from whole cells, no phosphorylation of tubulin could be detected on autoradiography of platelet proteins either in resting platelets or during thrombin-induced activation.

Identification of band 3-like proteins and Cl-/HCO3- exchange in isolated cardiomyocytes.

The identification of the protein that exerts the function of Cl-/HCO3- exchange is still unresolved in cardiac tissue. We have addressed this issue by using a multiple technical approach. Western blotting analysis with an antibody raised against human erythroid whole band 3 protein, the so-called protein that mediates the Cl-/HCO3- exchange in erythrocytes, showed that adult cardiomyocytes expressed two proteins immunologically related to the erythroid band 3.

Purification and characterization of erythrocyte caldesmon. Hypothesis for an actin-linked regulation of a contractile activity in the red blood cell membrane.

We have previously shown that in human or pig whole erythrocytes, only a single 71-kDa polypeptide cross-reacts with the affinity-purified antibody to pig platelet caldesmon (der Terrossian et al., 1989). In the present paper, we demonstrate that this polypeptide represents a genuine caldesmon which remains attached to the membrane prepared in the presence of an excess of free Mg2+ but not in its absence.