We have studied three low molecular weight phosphoproteins, ARPP-16, ARPP-19, and ARPP-21 (cAMPregulated phosphoproteins of Mr 16,000, 19,000, and 21,000, respectively) in reaggregate cultures from various regions of fetal mouse brain. ARPP-16 and ARPP-21 were detected only in striatal and cortical cultures. In contrast, ARPP-19, which is structurally related to ARPP-16, was also present in reaggregate cultures prepared from thalamus and ventral and dorsal mesencephalon, as well as in monolayer cultures of astroglial cells. In striatal aggregates cultured over a 3-week period, the relative levels of ARPP-16, ARPP-21, and synapsin I/protein HIa (synaptic vesicle-associated phosphoproteins closely related to each other and treated as a single entity in the present study) increased with time, whereas the level of ARPP-19 decreased. Incubation of striatal aggregates with 8-Br-cAMP, forskolin, or vasoactive intestinal peptide increased the phosphorylation of all these proteins. We conclude that the state of phosphorylation of two proteins enriched in specific neurons (ARPP-16 and ARPP-21) and two more widely distributed proteins (ARPP-19 and synapsin I/protein IIla) is regulated by cAMP and vasoactive intestinal peptide in striatal cells in culture. These phosphoproteins may therefore play a role in mediating some of the actions of vasoactive intestinal peptide in the caudate-putamen.

Phagocytosis has long been recognized as one of the differentiated functions of the macrophage and yet many of the cellular and biochemical mechanisms underlying this process remain unclear. Rabinovitch has separated the process of phagocytosis into two phases: attachment and ingestion (1). The former is dependent both on the surface properties of the cell and on the particle and is independent of energy and divalent cations, while the ingestion phase requires energy and divalent cations. Attachment can be mediated through binding to receptors on the macrophage surface for the C3 component of complement and the Fc portion of immunoglobulins. In studies on Fc-mediated and

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Red blood cell (RBC) protein 4.2 deficiency is often associated with a moderate nonimmune hemolytic anemia, splenomegaly, and osmotically fragile RBCs resembling, but not identical to, hereditary spherocytosis (HS). In the Japanese type of protein 4.2 deficiency (protein 4.2Nippon), the anemia is associated with a point mutation in the protein 4.2 cDNA. In this report, we describe a patient with moderate and apparently episodic nonimmune hemolytic anemia with splenomegaly, spherocytosis, osmotically fragile RBCs, reduced whole cell deformability, and abnormally dense cells. Sodium dodecyl sulfate- polyacrylamide gel electrophoresis analysis of the proposita's RBC membrane proteins showed an 88% deficiency of protein 4.2 and a 30% deficiency of glyceraldehyde-3-phosphate dehydrogenase (band 6). Structural and molecular analyses of the proposita's protein 4.2 were normal. In contrast, limited tryptic digestion of the proposita's band 3 showed a homozygous abnormality in the cytoplasmic domain. Analysis of the pedigree disclosed six members who were heterozygotes for the band 3 structural abnormality and one member who was a normal homozygote. Direct sequence analysis of the abnormal band 3 tryptic peptide suggested that the structural abnormality resided at or near residue 40. Sequence analysis of the proposita's band 3 cDNA showed a 232G-->A mutation resulting in a 40glutamic acid-->lysine substitution (band 3Montefiore). Allele-specific oligonucleotide hybridization was used to probe for the mutation in the pedigree, showing that the proposita was homozygous, and the pedigree members who were heterozygous for the band 3 structural abnormality were also heterozygous for the band 3Montefiore mutation. The band 3Montefiore mutation was absent in 26 chromosomes from race-matched controls and in one pedigree member who did not express the band 3 structural abnormality. In coincidence with splenectomy, the proposita's anemia was largely corrected along with the disappearance of most spherocytes and considerable improvements of RBC osmotic fragility, whole cell deformability, and cell density. We conclude that this hereditary hemolytic anemia is associated with the homozygous state for band 3Montefiore (40glutamic acid-->lysine) and a decreased RBC membrane content of protein 4.2. We speculate that band 3 structural abnormalities can result in defective interactions with protein 4.2 and band 6, and in particular, that the region of band 3 containing 40glutamic acid is involved directly or indirectly in interactions with these proteins.