title: Alternative splicing of an amino-terminal PEVK-like region generates multiple isoforms of Drosophila projectin.
abstract: Drosophila projectin is an extremely large protein found within the muscle sarcomeric unit, parallel with the actin and myosin filaments. Projectin has been suggested as the elastic component of C-filaments in insect indirect flight muscles, which is consistent with its localization from the Z band to the tip of the A band in these muscles. Here, we describe the completion of the projectin sequence analysis, which defines projectin as a 1 MDa protein, composed of 39 immunoglobulin and 39 fibronectin III domains. This analysis led also to the identification of a domain rich in the amino acids P, E, V and K within the NH(2) terminus of projectin. The length of the projectin PEVK-like region varies from 100 to 624 amino acid residues, following a complex pattern of alternative splicing events. PEVK domains were first identified in vertebrate titin and they have been associated with the elasticity of the protein. The PEVK-like domain of the projectin isoforms in indirect flight muscles may contribute to the elastic function of the C-filaments. The synchronous projectin isoforms contain a PEVK-like region, and the possible non-elastic function(s) of this domain in synchronous muscles are discussed.
authors.affiliation: College of Charleston, Charleston, SC 29424, USA.
authors.forename: R
authors.initials: R
authors.lastname: Southgate
authors.forename: A
authors.initials: A
authors.lastname: Ayme-Southgate
mesh_terms: D017398:Alternative Splicing / Q000235:genetics*; D000595:Amino Acid Sequence; D001483:Base Sequence; D064211:Connectin; D029721:Drosophila Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D004548:Elasticity; D005091:Exons / Q000235:genetics; D005353:Fibronectins / Q000737:chemistry; D017344:Genes, Insect / Q000235:genetics; D016678:Genome; D007136:Immunoglobulins / Q000737:chemistry; D007438:Introns / Q000235:genetics; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011494:Protein Kinases / Q000737:chemistry; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D013379:Substrate Specificity
chemical_list: D064211:Connectin; D029721:Drosophila Proteins; D005353:Fibronectins; D007136:Immunoglobulins; D009124:Muscle Proteins; D020033:Protein Isoforms; C078033:projectin; D011494:Protein Kinases