Naslov
PDZK1: I. a major scaffolder in brush borders of proximal tubular cells

Autori
Gisler, S.M. ; Pribanić, S. ; Bačić, Deša ; Forrer, P. ; Gantenbein, A. ; Sabourin, L.A. ; Tsuji, A. ; Zhao, Z.S. ; Manser, E. ; Biber, J. ; Murer H.

Izvornik
Kidney International (0085-2538) 64 (2003), 5; 1733-1745

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
renal transport of phosphate; NaPi-IIa; NaPi-I; PDZK1; NHERF-1; D-AKAP2; PDZ proteins; MAP17; URAT1; CFEX; yeast two-hybrid

Sažetak
BACKGROUND: In proximal tubular cells, PDZK1 (NaPi-Cap1) has been implicated in apical expression of the Na+-dependent phosphate cotransporter (NaPi-IIa) via interaction with its C- terminus. PDZK1 represents a multidomain protein consisting of four PDZ domains and thus is believed to have a broader specificity besides NaPi-IIa. METHODS: We subjected single PDZ domains derived from PDZK1 either to yeast two-hybrid screens or yeast trap assays. Different pull-down assays and blot overlays were applied to corroborate the PDZK1-mediated interactions in vitro. Co-localization of interacting proteins with PDZK1 in proximal tubular cells was assessed by immunohistochemistry. RESULTS: In the yeast screens, the most abundant candidate protein to interact with PDZK1 was the membrane-associated protein of 17 kD (MAP17). Besides MAP17, C-terminal parts of following transporters were also identified: NaPi-IIa, solute carrier SLC17A1 (NaPi-I), Na+/H+ exchanger (NHE-3), organic cation transporter (OCTN1), chloride-formate exchanger (CFEX), and urate-anion exchanger (URAT1). In addition, other regulatory factors were found among the clones, such as a protein kinase A (PKA)-anchoring protein (D-AKAP2) and N+/H+ exchanger regulator factor (NHERF-1). All interactions of itemized proteins with PDZK1 were affirmed by in vitro techniques. Apart from PDZK1, strong in vitro interactions of NHERF-1 were also observed with the solute transporters (excluding MAP17) and D-AKAP2. All identified proteins were immunolocalized in proximal tubular cells, wherein all membrane proteins co-localized with PDZK1 in brush borders. CONCLUSION: We hypothesize that PDZK1 and NHERF-1 establish an extended network beneath the apical membrane to which membrane proteins and regulatory components are anchored.

Izvorni jezik
Engleski

Znanstvena područja
Temeljne medicinske znanosti

POVEZANOST RADA