apical membrane


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apical membrane

the microvilli-bearing portion of the epithelial cell membrane at the secretory pole.
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AVP binds to V2R, present in the basolateral membrane of renal collecting duct principal cells and connecting tubule cells (Fenton et al., 2007; Mutig et al., 2007), inducing a signaling cascade, involving Gs protein mediated activation of adenylate cyclase, a rise in intracellular cAMP, activation of protein kinases, and redistribution of AQP2 water channels from intracellular vesicles to the apical membrane (Kuwahara et al., 1995; Katsura et al., 1997).
Accumulation of gentamicin in proximal tubule cells is due to the existence of an apical membrane endocytic complex involving the proteins megalin and cubilin (6).
Whereas in the presence of ADH the apical membrane of the collecting duct cell showed increased permeability of water through AQP, sodium through apical sodium channels, and urea through vasopressin-regulated urea transporters on the apical membrane of epithelium which, in turn, involved in excretion of less volume of urine.
Located at the apical membrane of the thyrocyte, this is essential for thyroid hormone synthesis, catalysis of iodine oxidation:
To measure chloride efflux rate across the apical membrane, the apical perfusion medium was changed with a medium in which chloride was substituted with isoosmotic nitrate.
TPO staining was strong and diffuse within the cytoplasm ofthyrocytes and was also observed in the apical membrane of all follicles of the ectopic samples examined, similar to normal thyroid tissue.
ABSTRACT: Malaria is endemic in Pakistan but little research data is available on vaccine candidate antigens like Apical membrane antigen 1 (AMA-1), Circumsporozoite protein (CSP), Merozoite surface protein 1 (MSP-1) and Duffy binding protein.
Our previous study indicated that CBS treatment had a beneficial effect on 17[alpha]-ethynylestradiol-(EE-) induced intrahepatic cholestasis rats and significantly increased the mRNA and protein expressions of multidrug resistance-associated protein 2 (MRP2) and breast cancer resistance protein (BCRP), both important proteins on the apical membrane of hepatocytes involving in the transport of bile acids, bilirubin, drugs, and so on [9].
It is important to mention that our present work emphasizes the NKCC2 expression in the apical membrane where the protein is functional.
Moreover, in the lumen of the organ, thread-like structures resembling a cellular bilayer membrane were also evident and were associated with the microvilli and cilia and even within the cytoplasm of epithelial cells (Figures 4(d), 4(e), and 4(f)); many of these threads spanned the distance between cilia, microvilli, and the apical membrane, building an apparent scaffold.
In contrast, the salt-secreting gill epithelial cells of brine shrimp, Artemia salina (Copeland 1967), the epithelial cells of the pereopodal discoid osmoregulatory organ of esturine amphoid, Melita setiflagella (Kikuchi & Matsumasa 1995), and the epithelial cells of the anal papillae of the saltwater mosquito larva, Aedes campestris (Meredith & Phillips 1973), are characterized by shallow apical membrane infoldings that are not closely associated with mitochondria.
In order to secrete chloride across the apical membrane of the epithelial cells, the basolateral membrane has to establish a driving force for anion efflux via anion channels (e.g., cystic fibrosis transmembrane conductance regulator, CFTR, or [Ca.sup.2+]-sensitive chloride channels) located in the apical membrane (Figure 2).