title: A Drosophila gene encoding multiple splice variants of Kazal-type serine protease inhibitor-like proteins with potential destinations of mitochondria, cytosol and the secretory pathway.
abstract: A Drosophila gene (KAZ1), mapped to cytological position 61A1-2 on chromosome 3, has been cloned and found to encode multiple splice variants of Kazal-type serine protease inhibitor-like proteins. KAZ1 consists of five exons and four alternatively retained introns to produce six transcripts of type AB, C1, C2, C3, D and E. The AB transcript contains two ORFs, of which the upstream one produces a polypeptide alpha, which has a mitochondrial sorting signal. Localization to mitochondria was confirmed by expression in COS1 cells. The downstream ORF is shared partially with type C1, C2, C3, D and E transcripts and produces polypeptides beta, gamma, delta and epsilon when expressed in Drosophila cells. Type C1, C2 and C3 transcripts differ only in the 5'-noncoding sequence and thus all produce type gamma. Polypeptides gamma and epsilon have a signal sequence at their N-termini and are secreted into the medium while beta and delta lack this sequence and remain in the cytoplasm. Isoforms beta and epsilon share a common C-terminal sequence distinct from that shared by polypeptides gamma and delta. The N-terminal sequences of isoforms beta to epsilon contain a PEST region which could induce rapid intracellular degradation of isoforms beta and delta. Sequence analysis of the Kazal-type domain suggests a similar folding pattern as observed for rhodniin and SPARC/BM-40. Northern analysis and in situ hybridization showed that the type C3 transcript is predominant and the expression is highest in midgut at larval stage.
authors.affiliation: Nagoya University Bioscience Center, Nagoya University, Chikusa, Nagoya, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Niimi
authors.forename: H
authors.initials: H
authors.lastname: Yokoyama
authors.forename: A
authors.initials: A
authors.lastname: Goto
authors.forename: K
authors.initials: K
authors.lastname: Beck
authors.forename: Y
authors.initials: Y
authors.lastname: Kitagawa
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002451:Cell Compartmentation; D002522:Chlorocebus aethiops; D003001:Cloning, Molecular; D003600:Cytosol / Q000378:metabolism; D029721:Drosophila Proteins; D004331:Drosophila melanogaster / Q000235:genetics* / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D017344:Genes, Insect; D019476:Insect Proteins / Q000235:genetics* / Q000378:metabolism; D007438:Introns / Q000235:genetics; D008928:Mitochondria / Q000378:metabolism; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000235:genetics* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012326:RNA Splicing; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid
chemical_list: D029721:Drosophila Proteins; D019476:Insect Proteins; C402608:KAZ1 protein, Drosophila; D020033:Protein Isoforms; D011993:Recombinant Fusion Proteins