High impact information on Myo1a

• We now report that endocytosis of these immunoglobulins is mediated by cell surface binding to brush border myosin (myosin 1) [1].
• An affinity-purified polyclonal antibody to brush border myosin I colocalizes with a polypeptide of 120 kD in fibroblast extracts [2].
• The analysis at the ultrastructural level of cells producing these brush border myosin I truncated proteins shows that the delivery of the fluid phase markers from endosomes to lysosomes is impaired [3].
• We also show that truncated brush border myosin I proteins, myosin Is that share 78% homology with MMIalpha, promote the dissociation of MMIalpha from vesicular membranes derived from endocytic compartments [3].
• The isolated intestinal microvillus cytoskeleton (core) consists of four major proteins: actin, villin, fimbrin and brush border myosin-I [4].

Biological context of Myo1a

• This is in marked contrast to chicken, where brush border myosin-I expression begins early in embryogenesis [5].
• Of these components, villin and brush border myosin-I show tissue-specific expression, so they may be involved in the morphogenesis of intestinal microvilli [4].
• The binding sites of the antibodies on the rod portion of brush border myosin were localised using rotary shadowing/electron microscopy of myosin-antibody complexes [6].

Anatomical context of Myo1a

• The deduced primary structure of mouse brush border myosin-I is homologous to other known brush border myosins-I [5].
• This suggests that brush border myosin-I may be targeted to the plasma membrane on Golgi-derived vesicles rather than by direct targeting to microvillar actin cores [5].
• Brush border myosin-I microinjected into cultured cells is targeted to actin-containing surface structures [4].
• Since some endogenous myosin-Is have been found associated with cytoplasmic vesicles, these results show that brush border myosin-I has a domain that specifically targets it to the plasma membrane in both intestinal and cultured cell systems [4].
• Although subtle ultrastructural abnormalities can be detected in the actin cores of small intestinal microvilli, localization of sucrase isomaltase, brush border myosin I, and zonula occludens I to the microvillar surface of the small intestine is normal [7].

Other interactions of Myo1a

• Using RT-PCR, we found prominent expression of three isozymes, Myo1b (also known as myosin-Ia or myr 1) [8].

Analytical, diagnostic and therapeutic context of Myo1a

• Northern blot, immunoblot, and immunolocalization studies indicate that the intestine-specific and subcellular localization profile of mouse brush border myosin-I are comparable to that determined for other brush border myosins-I [5].
• Solid-phase assays, western blots and immunofluorescence were used to study the cross-reactivity of these monoclonal antibodies against a variety of myosins from different species and cell types, to assess the immunological relatedness between brush border myosin and homologous molecules present in different tissues and species [6].

References