title: Brush-border alpha-actinin? Comparison of two proteins of the microvillus core with alpha-actinin by two-dimensional peptide mapping.
abstract: The bundle of filaments within the intestinal microvillus contains four major polypeptides in addition to actin calmodulin, a 70-kdalton subunit and two polypeptides with molecular masses similar to that of the Z-line component alpha-actinin (95 and 105 kdaltons). Two-dimensional mapping of tryptic peptides indicates that (a) alpha-actinins from chicken skeletal, cardiac, and smooth muscle are similar but not identical proteins and that skeletal alpha-actinin in more similar to the cardiac subunit than to the alpha-actinin from gizzard; (b) the brush-border 95- and 105-kdalton subunits are closely related to each other, but the smaller subunit is not a proteolytic fragment of the 105-kdalton subunit; and (c) although there is considerable peptide overlap between the brush-border subunits and the three alpha-actinins, the peptide maps of the 95- and 105-kdalton proteins are substantially distinct from the various alpha-actinin maps, suggesting that neither brush-border subunit is a bona fide alpha-actinin. Nevertheless, on the basis of peptide mapping criteria alone, one cannot exclude the possibility that the brush-border subunits are "alpha-actinin-like." However, there is no immunological cross-reactivity between the brush-border subunits and alpha-actinins, using antibodies prepared against gizzard alpha actinin.
mesh_terms: D000185:Actinin / Q000032:analysis* / Q000276:immunology; D000818:Animals; D002462:Cell Membrane / Q000032:analysis*; D002645:Chickens; D003429:Cross Reactions; D008871:Microvilli / Q000032:analysis*; D008970:Molecular Weight; D009124:Muscle Proteins / Q000032:analysis*; D009130:Muscle, Smooth / Q000032:analysis; D009132:Muscles / Q000032:analysis; D009206:Myocardium / Q000032:analysis; D010446:Peptide Fragments / Q000032:analysis
chemical_list: D009124:Muscle Proteins; D010446:Peptide Fragments; D000185:Actinin