title: Molecular characterization of a PDZ-LIM protein in Atlantic salmon (Salmo salar): a fish ortholog of the alpha-actinin-associated LIM-protein (ALP).
abstract: A protein containing both PDZ and LIM protein-protein interaction motifs has for the first time been identified in a lower vertebrate species. A full-length cDNA encoding the ortholog of the alpha-actinin-associated LIM protein (ALP) was isolated from white skeletal muscle of Atlantic salmon (Salmo salar). Whereas ALP is expressed as two muscle specific isoforms in mammals and chicken as the result of alternative splicing, a single ALP transcript was found in both muscle and non-muscular tissues of Atlantic salmon. On the other hand, Western blot analysis revealed several immunoreactive ALP variants in salmon muscle tissues, including a 45 kDa protein in white and red skeletal muscle and a 37-40 kDa protein in heart and smooth muscle. Salmon ALP and alpha-actinin showed similar striated patterns in serial longitudinal sections of white and red skeletal muscle and heart muscle. Expression of ALP was initiated at the 45-somite stage of the salmon embryogenesis contemporary with the first appearance of alpha-actinin transcripts. The similarities in both the spatial and temporal expression patterns of salmon ALP and alpha-actinin strongly indicate that the two proteins are associated as in higher vertebrates, and that the assumed involvement of ALP in the organization and/or maintenance of the Z-lines in striated muscle has been conserved during vertebrate evolution. However, in contrast to the restricted expression of ALP in higher vertebrates, the ubiquitous expression of salmon ALP suggest that this factor is involved in the assembly of additional multi-protein complexes in fish.
authors.affiliation: Institute of Aquaculture Research, P.O. Box 5010, N-1432 Aas, Norway. oivind.andersen@akvaforsk.nlh.no
authors.forename: Øivind
authors.initials: Ø
authors.lastname: Andersen
authors.forename: Tone-Kari
authors.initials: TK
authors.lastname: Østbye
authors.forename: Irene
authors.initials: I
authors.lastname: Gabestad
authors.forename: Christer
authors.initials: C
authors.lastname: Nielsen
authors.forename: Tora
authors.initials: T
authors.lastname: Bardal
authors.forename: Trina Falck
authors.initials: TF
authors.lastname: Galloway
mesh_terms: D000185:Actinin / Q000737:chemistry* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D002645:Chickens; D003001:Cloning, Molecular; D015870:Gene Expression; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D051379:Mice; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000032:analysis / Q000235:genetics* / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism*; D018008:Myogenin / Q000235:genetics / Q000378:metabolism; D009928:Organ Specificity; D017434:Protein Structure, Tertiary / Q000235:genetics / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D020317:Salmo salar / Q000196:embryology; D017386:Sequence Homology, Amino Acid
chemical_list: C503799:MYOG protein, human; D009124:Muscle Proteins; C503801:Myog protein, mouse; D018008:Myogenin; D012333:RNA, Messenger; D011994:Recombinant Proteins; D000185:Actinin