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A ankyrin proteins encoded by the Ank1 gene were detected in the sarcoplasmic reticulum of the rat and rabbit skeletal muscle by immunofluorescence utilizing p6 antibodies and monoclonal antibodies. The ankyrin proteins exhibited a large NH2-terminal domain that mediated the binding to integral membrane proteins. The ankyrin protein also contained a central domain responsible for binding spectrin and a COOH-terminal domain that exhibited regulatory functions.

Reverse transcription PCR amplification and sequencing of the erythroid beta-spectrin transcript from the spleen of mutant ja/ja jaundiced mice reveals that a point mutation in the arginine codon releases a stop codon in the mRNA that encodes the repeat 9 of beta-spectrin at 1160 amino acid location. The point mutation induces a Dde I site in the PCR-amplified DNA of ja/ja mice, but not in control mice, in which mutation repair is done using 53 backcrossing generations. The point mutation-induced beta-spectrin mRNA level reduction results in severe hemolytic anemia in jaundiced mice.

Examines on presence of small ankyrins in rat and rabbit skeletal muscle and their selective association with the sarcoplasmic reticulum. Three distinct structural domains of ankyrin; Transfection of the small ankyrins in HEK 293 cells; Factor that is responsible for some forms of human hereditary spherocytosis.

Tetramers of alpha- and beta-spectrin heterodimers, linked by intermediary proteins to transmembrane proteins, stabilize the red blood cell cytoskeleton. Deficiencies of either alpha- or beta-spectrin can result in severe hereditary spherocytosis (HS) or hereditary elliptocytosis (HE) in mice and humans. Four mouse mutations, sph, sph(Dem), sph(2BC), and sph(J), affect the erythroid alpha-spectrin gene, Spna1, on chromosome 1 and cause severe HS and HE. Here we describe the molecular alterations in alpha-spectrin and their consequences in sph(2BC)/sph(2BC) and sph(J)/sph(J) erythrocytes. A splicing mutation, sph(2BC) initiates the skipping of exon 41 and premature protein termination before the site required for dimerization of alpha-spectrin with beta-spectrin. A nonsense mutation in exon 52, sph(J) eliminates the COOH-terminal 13 amino acids. Both defects result in instability of the red cell membrane and loss of membrane surface area. In sph(2BC)/sph(2BC), barely perceptible levels of messenger RNA and consequent decreased synthesis of alpha-spectrin protein are primarily responsible for the resultant hemolysis. By contrast, sph(J)/sph(J) mice synthesize the truncated alpha-spectrin in which the 13-terminal amino acids are deleted at higher levels than normal, but they cannot retain this mutant protein in the cytoskeleton. The sph(J) deletion is near the 4.1/actin-binding region at the junctional complex providing new evidence that this 13-amino acid segment at the COOH-terminus of alpha-spectrin is crucial to the stability of the junctional complex.