摘要
Protein kinase C （PKC） consists of a family of serine/threonine kinases that are identified by the presence of two copies of the C1 domain, which form the diacylglycerol （DAG）-binding module. According to their enzymatic activities PKCs are sub-divided into conventional isozymes （PKCα, β and γ; calcium, phospholipid and DAG-activated kinases）, novel isozymes （PKCδ, ε, η, μ and θ; calcium-insensitive, phospholipid-dependent and DAG-dependent）, and atypical isozymes （PKCζ and λ; calcium-insensitive and DAG-insensitive enzymes）. Human protein kinase Cμ and its mouse homolog, protein kinase D1 （PKD1）, which has been under intense investigation in recent years, is a DAG-dependent, Ca^2＋-independent serine/threonine protein kinase as a novel PKC isoform. Recently PKDs were classified as a novel subgroup of the calcium/calmodulin-dependent protein kinase （CAMK） family, based on sequence similarities of the kinase domain; the catal^ctic domain of PKD1 has the highest homology to CAMK. PKD1 has three main pathways for activation. One is DAG-phospholipase C （PLC）-PKC-dependent activation of PKD1. In this model, PKD 1 not only acts as a direct DAG target but also lies downstream of PKCs to regulate biological processes in cells.
Protein kinase C （PKC） consists of a family of serine/threonine kinases that are identified by the presence of two copies of the C1 domain, which form the diacylglycerol （DAG）-binding module. According to their enzymatic activities PKCs are sub-divided into conventional isozymes （PKCα, β and γ; calcium, phospholipid and DAG-activated kinases）, novel isozymes （PKCδ, ε, η, μ and θ; calcium-insensitive, phospholipid-dependent and DAG-dependent）, and atypical isozymes （PKCζ and λ; calcium-insensitive and DAG-insensitive enzymes）. Human protein kinase Cμ and its mouse homolog, protein kinase D1 （PKD1）, which has been under intense investigation in recent years, is a DAG-dependent, Ca^2＋-independent serine/threonine protein kinase as a novel PKC isoform. Recently PKDs were classified as a novel subgroup of the calcium/calmodulin-dependent protein kinase （CAMK） family, based on sequence similarities of the kinase domain; the catal^ctic domain of PKD1 has the highest homology to CAMK. PKD1 has three main pathways for activation. One is DAG-phospholipase C （PLC）-PKC-dependent activation of PKD1. In this model, PKD 1 not only acts as a direct DAG target but also lies downstream of PKCs to regulate biological processes in cells.
