Chromosomes Human chromosome

Chorionic Somatomammotropin. Three genes encode human chorionic somatomammotropin [11085-36-2] (hCS). These are located within a cluster of genes on human chromosome 17 which code for pituitary growth hormone [12629-01 -5] (GH-N), placental GH [109675-94-7J (GH-V), and three hCS molecules, ie, hCS-A, hCS-B, and hCS-V (1 3), also referred to as human placental lactogens. All of these molecules ate closely related to GH in stmcture (Fig. 1). Placental lactogens also exist in rodents and mminants however, these hormones are more closely related to prolactin than GH. 

FIGURE 12.31 A model for chromosome structure, human chromosome 4. The 2-um DNA helix is wound twice around histone octamers to form 10-um uucleosomes, each of which contains 160 bp (80 per turn). These uucleosomes are then wound in solenoid fashion with six uucleosomes per turn to form a 30-nm filament. In this model, the 30-nm filament forms long DNA loops, each containing about 60,000 bp, which are attached at their base to the nuclear matrix. Eighteen of these loops are then wound radially around the circumference of a single turn to form a miniband unit of a chromosome. Approximately 10 of these minibands occur in each chromatid of human chromosome 4 at mitosis. 

The human leucocyte antigen (HLA) system is the general name of a group of genes in the human major histocompatibility complex (MHC) region on human chromosome 6 (mouse chromosome 17) that encodes the cell-surface antigen-presenting proteins. 

Type IEI IFNs, also named EFN-kl, -k2, and -k3 or EL-28A, B, and IL-29, respectively also display EFN-like activities and are induced by most viruses that also give rise to type I EFN production. The genes are located on human chromosome 1 and contain several introns. EFN-k binds to two receptor chains distinct from type I and type II EFNs named EFNLR-1 and IL-10R2 the latter being a common chain for EL-10 and IL-22. Signaling... 

Chromosome Human 14q11.2—q12 Human Xq13.2-21.1 Human 13q14.12-q21.1... 

Recently, a novel class of type 1-like human IFNs, named 1FN-A,1 or lL-29,1FN-A.2 (1F-28A) and 1FN-X3 (1F-28B), was identified (Dumoutier et al. 2003 Sheppard et al. 2003). The three IFN-A, genes cluster on human chromosome 19 and comprise 5 exons for 1FN-A,1 and 6 for 1FN-A.2 and 1FN-A.3, and several introns (Table 1). They encode 20- to 22-kDa secreted monomeric proteins of 196 to 200 amino acids. Type 111 IFNs have also been identified in other species such as mice, birds, and fish. 

Figure 36-5. The two sister chromatids of human chromosome 12 (x 27,850). The location of the A+T-rich centromeric region connecting sister chromatids is indicated, as are two of the four telomeres residing at the very ends of the chromatids that are attached one to the other at the centromere. (Modified and reproduced, with permission, from DuPraw EJ DNA and Chromosomes. Holt, Rinehart, and Winston, 1970.)...

Figure 36-12. Sister chromatid exchanges between human chromosomes. These are detectabie by Giemsa staining of the chromosomes of ceiis repiicated for two cycies in the presence of bromodeoxyuridine. The arrows indicate some regions of exchange. (Courtesy of S Wolff and J Bodycote.)...

Radiation hybrid mapping Now the most rapid method of localizing a gene or DNA fragment to a subregion of a human chromosome and constructing a physical map. 

The Physiome Project will undoubtedly benefit from lessons learned during the progress of the Genome Project, in particular, that big visions and small steps (at least initially) are not necessarily a contradiction. It will, however, have to develop a completely different approach to problem solving than that used for the Genome Project, as neither the total dimension of the task (there are only 23 human chromosome pairs) nor the size of the smallest component that needs investigating (DNA bases) can be defined at the outset of the Physiome Project. 

The gene encoding SERCAl is on human chromosome 16 [61] a selective defect in its expression is the cause of Brody s disease [62-66]. 

Wright WE et al. (1997) Normal human chromosomes have long G-rich telomeric overhangs at one end. Genes Dev ll(21) 2801-2809... 

Buettner J., Glusman G., Ben-Arie N., Ramos, P., et al. (1998). Organization and evolution of olfactory receptor genes on human chromosome 11. Genomics 53, 56-68. 

H21. Howard, T. D., Akots, G., and Bowden, D. W., Physical and genetic mapping of the muscle phos-phofructokinase gene (PFKM) Reassignment to human chromosome 12q. Genomics 34, 122-127(1996). 

FIG. 3. Chromosome arms begin to separate in pro metaphase. Scanning electron micrographs of human chromosomes isolated from cells in prophase (A), prometaphase (B), metaphase (C) and early anaphase (insert in C). Size bar, 1 /tm. Reprinted with permission from Sumner (1991). 

The H2 receptor is the second class of HA receptors. This is another G-protein-coupled receptor but, unlike the Hi receptor, the H2 receptor is coupled to adenylyl cyclase via the GTP-binding Gs protein (Hill et ah, 1997). Encoded by an intronless gene and located on human chromosome 5, the H2 receptor is made up of c. 358 amino acids (Gantz et ah, 1991 Traiffort et ah, 1995). Activation of the H2 receptor causes an accumulation of cAMP and activation of protein kinase A that eventually leads to the activation of cyclic-AMP-response element (CRE)-binding protein (CREB) (Hill et ah, 1997). In neurons, the H2 receptor mediates its excitatory effects by blocking the Ca2+-dependent K+ channel (Haas Konnerth, 1983). 

Most of the DNA of animal cells is found in the nucleus, where DNA is the major constituent of the chromosomes. On the other hand, most of the RNA is located in the cytoplasm. Nuclear DNA exists as a thin, double helix only 2 nm wide. The double helix is folded and complexed with protein to form chromosomal strands approxim-ately 100 to 200 nm in diameter. Each chromosome contains a single DNA duplex. The human chromosomes vary in size the smallest contains approximately 4.6 X 10 base pairs of DNA, and the largest 2.4 X 10 base pairs. In contrast, the Escherichia coli chromosome has 4.5 x 106 base pairs. The DNA of die chromosomes is tightly packed and associated with both histone and nonhistone proteins. 

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