PKCζ-interacting protein ZIP3 is generated by intronic polyadenylation, and is expressed in the brain and retina of the rat.
Scaffold proteins contain multiple protein-protein interaction modules that physically assemble functionally related proteins into larger complexes. ZIPs [PKC (protein kinase C) ζ-interacting proteins] link the enzymatic activity of the atypical PKC isoforms PKCλ/ι or PKCζ to target proteins and are associated with neurodegenerative disorders. In the rat, alternative splicing generates three ZIP variants. Previously, we identified the ZIP3 transcript, containing 13 C-terminal amino acids encoded by intron 4, in the rat CNS (central nervous system). In the present study, we identified intronic polyadenylation signals in rat and human ZIP genes [known as SQSTM1 (sequestosome-1) in humans] and detected the corresponding ZIP3-like transcripts. In addition, we generated ZIP3-specific immune sera and observed expression of the protein in the brain and retina of the adult rat. In the retina, ZIP3 is present in nuclear layers where it co-localizes with PKCζ. An immune serum recognizing all three ZIP isoforms labelled the same cells as the newly generated ZIP3-specific antibodies and, in addition, stained both synaptic layers of the retina. There, ZIPs are localized in axon terminals of rod bipolar cells that also contain ZIP-interacting PKCζ and GABA(C) (γ-aminobutyric acid type C) receptors. In summary, we detected ZIP3-like transcripts in rat- and human-derived samples and describe the expression of ZIP3 in the rat CNS.
Urbanczyk
Andreas
A
Institut für Biochemie (Emil-Fischer-Zentrum), Friedrich-Alexander-Universität Erlangen-Nürnberg, 91045 Erlangen, Germany.
Jünemann
Anselm
A
Enz
Ralf
R
D000818:Animals; D001923:Brain Chemistry; D006360:Heat-Shock Proteins / Q000032:analysis* / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D007438:Introns; D026723:Polyadenylation; D011493:Protein Kinase C / Q000032:analysis*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D012160:Retina / Q000737:chemistry*; D051245:Retinal Bipolar Cells / Q000737:chemistry; D000071456:Sequestosome-1 Protein; D014018:Tissue Distribution; D000099221:Protein Kinase C zeta
D006360:Heat-Shock Proteins; D007106:Immune Sera; D011493:Protein Kinase C; D012333:RNA, Messenger; D000071456:Sequestosome-1 Protein; D000099221:Protein Kinase C zeta; C491079:Sqstm1 protein, rat