A secreted inhibitor of angiogenesis that is controlled by a tumor suppressor gene in hamster cells has been found to be similar to a fragment of the platelet and matrix protein thrombospondin. The two proteins were biochemically similar and immunologically crossreactive and could substitute for one another in two functional assays. Human thrombospondin inhibited neovascularization in vivo and endothelial cell migration in vitro, as does the hamster protein, gpl40.

The CSF

We have isolated 5′ cDNA clones encoding a member of the cellular myosin heavy chain gene family from human leukocytes. The predicted amino acid sequence shows 93% identity to a chicken cellular myosin heavy chain, 76% to chicken smooth muscle, and 40% to human sarcomeric myosin heavy chain. The mRNA is expressed as a 7.4- to 7.9-kb doublet in many nonmuscle cells, and is upregulated in myeloid cell lines on induction from a proliferating to a differentiated state. Antisera raised against a peptide made from the predicted amino acid sequence specifically reacts with a 224-Kd polypeptide in leukocyte cell lines, and the protein is also upregulated during the induction of monocytic and granulocytic differentiation in these cells. The gene for this cellular myosin heavy chain maps to chromosome 22, bands q12.3-q13.1, demonstrating that it is not located in the previously described sarcomeric gene clusters on chromosomes 14 and 17. This cellular myosin heavy chain may be a major contractile protein responsible for movement in myeloid cell lines because no mRNA for sarcomeric myosin heavy chain is detected in these cells.

Abstract. Utilizing a eDNA clone encoding the oligodendrocyte-myelin glycoprotein (OMgp) to screen a human genomic DNA library, we have obtained a clone that contains the OMgp gene. The genornic clone was restriction mapped and the OMgp gene and its 5' and 3' flanking regions were sequenced. A single intron is found in the 5' untranslated region of the gene, while the coding region is uninterrupted by an intron. This placement of a single intron in the OMgp gene is identical to that of the gene for the o~-chain of platelet glycoprotein Ib, which, along with OMgp, belongs to a family of proteins sharing two distinct structural domains: an NH2-terminal cysteine-rich domain and an adjacent domain of tandem leucine-rich repeats. Hence, it is possible that this family of proteins is not only related in terms of primary structure, but also through similar gene structure. Sequence comparison of the 5' and 3' flanking regions did not reveal striking similarities to other DNA sequences, and no obvious promoter elements were noted. By hybridization of the genomic clone to metaphase cells, we have localized the human OMgp gene to chromosome 17 bands qll-12, a region to which the neurofibromatosis type 1 gene has been previously mapped.T HE oligodendrocyte-myelin glycoprotein (OMgp) ~ is a highly glycosylated protein of oligodendrocytes and central nervous system myelin which appears to be localized at the paranodal region of the myelin sheath (Mikol and Stefansson, 1988). OMgp is anchored in the plasma membrane as a 120-kD glycoslyphosphatidylinositol-linked form that can be released from the membrane upon incubation with phospholipase C to generate a soluble 105-kD polypeptide. Based on eDNA sequence, the predicted primary structure of OMgp consists of four domains (Mikol et al., 1990). At the NH2-terminus there is a 32-amino acid cysteine-rich (CR) motif. This is followed by a domain consisting of 7 I/2 tandem leucine-rich repeats (LRs) of 24 amino acids each, and a domain of 4 1/2 repeats of 40 residues each that are rich in serines and threonines. A hydrophobic COOH-terminal segment is most likely cleaved concomitant with the attachment of a phosphatidylinositolcontaining glycan (Cross, 1990).

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