Structural and Functional Investigation of p68 - A Protein of the Lipocortin/Calpactin Family
The recent discovery of a family of structurally related, calcium and phospholipid binding proteins has stimulated considerable interest in many laboratories, and invited wide-ranging hypotheses regarding their physiological functions (Crompton et al., 1988b, Klee 1988). The first proposals for the functions of two of these proteins were based on their apparent inducibility by glucocorticoids (as regulators of phos-pholipase A2 activity in inflammatory responses), and on their calcium-dependent association with actin (in bundling of actin filaments). The two proteins were thus named lipocortin and calpactin respectively, and these names have been adopted generically to describe the family. Six unique proteins have now been cloned and sequenced, and can be firmly placed in the lipocortin/calpactin family (Pepinsky et al., 1988). The elucidation of the structures of the individual members of the family, has come from groups with diverse interests, and this is reflected in the diversity of the proteins nomenclature (see Table 1). The five which fall into the 30 – 40kD molecular weight range are protein II, lipocortin I (p35), calpactin I (p36), lipocortin III and IBC (the inhibitor of blood coagulation). The sixth and largest member of the family, which will provide the focus of this manuscript, is p68 (67k-calelectrin).
KeywordsTyrosine Hexa Adenosine Electrophoresis Serine
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- Pepinsky, R.B., Tizard, R., Mattaliano, R.J., Sinclair, L.K., Miller, G.T., Browning, J.L., Chow, E.P., Burne, C., Huang, K-S., Pratt, D., Wachter, L., Hession, C., Frey, A.Z., and Wallner, B.P., 1988, Five distinct calcium and phospholipid binding proteins share homology with lipocortin I, J. Biol. Chem., 263:10799.PubMedGoogle Scholar