Rabbit Polyclonal Antibody to MARCKS Cat# RPCA-MARCKS

      Myristolyated alanine rich C-kinase substrate, hence MARCKS, was originally discovered by as a major substrate for protein kinase C in the brain and other tissues (1). The protein sequence is indeed unusually rich in alanine, the human sequence containing 30.7% alanine. It is also rich in glutamic acid (16.0%), proline (10.5%) and glycine (10.2%). The sequence has almost no hydrophobic amino acids and has a calculated molecular weight of 31.4kDa and PI of 4.46. These unusual features are responsible for the low SDS-PAGE mobility, which gives an apparent molecular weight of 80kDa. MARCKS belongs to the family of intrinsically unstructured proteins (IUP) which typically have a high content of glutamic acid and proline and low hydrophobic content (5). IUP proteins or regions with these properties within larger proteins hove no defined structure but adopt a defined conformation on binding to their ligands. MARCKS interacts with actin and calcium in a manner regulated by protein kinase C (2-4). It is a major protein of the brain concentrated in the synapses of neurons and is membrane localized due to the N-terminal lipid myristoyl group. Antibody to MARCKS can therefore be used as a marker of synaptic regions. Genetic knock out of MARCKS in transgenic mice is perinatal lethal and associated with aberrant brain development suggesting a fundamental importance in the CNS (6). Since the MARCKS protein sequence is relatively poorly conserved across species boundaries, antibodies to the human protein may not work well on rodent tissues, which is the case with this reagent.

Chromogenic immunostaining of a formalin fixed paraffin embedded human hippocampus section with rabbit pAb to MARCKS, RPCA-MARCKS, dilution 1:2,000, detected with DAB (brown) using the Vector Labs ImmPRESS method and reagents with citra buffer retrieval. In the hippocampus, RPCA-MARCKS labels the nuclei, membrane and cytoplasm of glial cells and the synapses of neuronal cells. This antibody performs well in the staining of NBF fixed human tissues but does not cross react with rodent. Mouse select image for larger view.

1. Hirai M, Shimizu N. Purification of two distinct proteins of approximate Mr 80,000 from human epithelial cells and identification as proper substrates for protein kinase C. Biochem. J. 270:583-9 (1990).
2. Hartwig JH, et al. MARCKS is an actin filament crosslinking protein regulated by protein kinase C and calcium-calmodulin. Nature 356:618-22 (1992).
3. Aderem A. The MARCKS Brothers: A Family of Protein Kinase C Substrates. Cell 71:713-6 (1992).
4. Blackshear PJ. The MARCKS family of cellular protein kinase C substrates. J. Biol. Chem. 268:1501-4 (1993).
5. Tompa P. Intrinsically unstructured proteins. Trends Biochem. Sci. 27:527-33 (2002).
6. Stumpo DJ, Bock CB, Tuttle JS, Blackshear PJ. MARCKS deficiency in mice leads to abnormal brain development and perinatal death. PNAS 92:944-8 (1995).