Immunolocalization of the 38.3 kDa calponin-like protein in stratified muscles of the tail of Schistosoma japonicum cercariae.
Calponins are proteins present in vertebrate smooth musculature where they occur in association with thin myofilaments. Calponins are not present in vertebrate or invertebrate striated muscles. The blood fluke Schistosoma japonicum expresses a 38.3-kDa protein that bears substantial homology with vertebrate calponin and occurs entirely within smooth musculature of adults. Calponin-like immunoreactivity has been demonstrated in smooth muscles of many invertebrate phyla. The Schistosoma japonicum calponin has been localised in smooth myofibrils of adults where it is associated with myofilaments and sarcoplasmic reticulum. In this study, the ultrastructural localisation of the protein in muscles of S. japonicum cercariae is described. The protein is present in smooth muscles of the forebody and the stratified muscle of the tail. Within the stratified layer, the protein occurs predominantly in transverse arrays of sarcoplasmic reticulum. The localisation data suggest that the calponin-like protein of S. japonicum is involved in contraction of the stratified tail muscle. Furthermore, the presence of a calponin system in the stratified muscle suggests that this muscle is simply a superior form of muscle, closely related to smooth muscles that use a caldesmin-calponin system in contraction.
Jones
M K
MK
Centre for Microscopy and Microanalysis, The University of Queensland, St Lucia, 4072, Brisbane, Queensland, Australia.
Yang
W
W
McManus
D P
DP
D008841:Actin Cytoskeleton / Q000737:chemistry; D000818:Animals; D015153:Blotting, Western; D002135:Calcium-Binding Proteins / Q000032:analysis* / Q000276:immunology; D015801:Helminth Proteins / Q000032:analysis / Q000276:immunology; D007150:Immunohistochemistry; D008840:Microfilament Proteins; D018482:Muscle, Skeletal / Q000737:chemistry / Q000648:ultrastructure; D009130:Muscle, Smooth / Q000737:chemistry / Q000648:ultrastructure; D009210:Myofibrils / Q000737:chemistry; D012519:Sarcoplasmic Reticulum / Q000737:chemistry; D012549:Schistosoma japonicum / Q000737:chemistry* / Q000648:ultrastructure; D000096985:Calponins
D002135:Calcium-Binding Proteins; D015801:Helminth Proteins; D008840:Microfilament Proteins; D000096985:Calponins