Identification of a novel human tankyrase through its interaction with the adaptor protein Grb14.

Tankyrase is an ankyrin repeat-containing poly(ADP-ribose) polymerase originally isolated as a binding partner for the telomeric protein TRF1, but recently identified as a mitogen-activated protein kinase substrate implicated in regulation of Golgi vesicle trafficking. In this study, a novel human tankyrase, designated tankyrase 2, was isolated in a yeast two-hybrid screen as a binding partner for the Src homology 2 domain-containing adaptor protein Grb14. Tankyrase 2 is a 130-kDa protein, which lacks the N-terminal histidine/proline/serine-rich region of tankyrase, but contains a corresponding ankyrin repeat region, sterile alpha motif module, and poly(ADP-ribose) polymerase homology domain. The TANKYRASE 2 gene localizes to chromosome 10q23.2 and is widely expressed, with mRNA transcripts particularly abundant in skeletal muscle and placenta. Upon subcellular fractionation, both Grb14 and tankyrase 2 associate with the low density microsome fraction, and association of these proteins in vivo can be detected by co-immunoprecipitation analysis. Deletion analyses implicate the N-terminal 110 amino acids of Grb14 and ankyrin repeats 10-19 of tankyrase 2 in mediating this interaction. This study supports a role for the tankyrases in cytoplasmic signal transduction pathways and suggests that vesicle trafficking may be involved in the subcellular localization or signaling function of Grb14.

Integrin-linked kinase regulates phosphorylation of serine 473 of protein kinase B by an indirect mechanism.

The serine threonine kinase protein kinase B regulates cellular activities as diverse as glycogen metabolism and apoptosis. Full activation of protein kinase B requires 3-phosphoinositides and dual phosphorylation on threonine-308 and serine-473. CaM-K kinase and 3-phosphoinositide dependent-kinase-1 phosphorylate threonine-308. Integrin-linked kinase reportedly phophorylates serine-473. Consistent with this, in a model COS cell system we show that expression of wild-type integrin-linked kinase promotes the wortmannin sensitive phosphorylation of serine-473 of protein kinase B and its downstream substrates, and inhibits C2-ceramide induced apoptosis. In contrast, integrin-linked kinase mutated in a lysine residue critical for function in protein kinases is inactive in these experiments, and furthermore, acts dominantly to block serine-473 phosphorylation induced by ErbB4. However, alignment of analogous sequences from different species demonstrates that integrin-linked kinase is not a typical protein kinase and identifies a conserved serine residue which potentially regulates kinase activity in a phosphorylation dependent manner. Mutation of this serine to aspartate or glutamate, but not alanine, in combination with the inactivating lysine mutation restores integrin-linked kinase dependent phosphorylation of serine-473 of protein kinase B. These data strongly suggest that integrin-linked kinase does not possess serine-473 kinase activity but functions as an adaptor to recruit a serine-473 kinase or phosphatase.

Size parameter for thermally emitting particles.

For thermal emission from particles the conventional size parameter X = 2 pi a/lambda does not distinguish between small and large particles. We show that the opacity parameter Omega = 4 pi ka/lambda = 2 kX is a more accurate means of demarcating the two emission regimes. Omega is approximately equal to the particle's mean optical depth, and it can be derived from both scattering theory and geometrical optics.

Spatial Organization and Time Dependence of Jupiter's Tropospheric Temperatures, 1980-1993.

The spatial organization and time dependence of Jupiter's temperatures near 250-millibar pressure were measured through a jovian year by imaging thermal emission at 18 micrometers. The temperature field is influenced by seasonal radiative forcing, and its banded organization is closely correlated with the visible cloud field. Evidence was found for a quasi-periodic oscillation of temperatures in the Equatorial Zone, a correlation between tropospheric and stratospheric waves in the North Equatorial Belt, and slowly moving thermal features in the North and South Equatorial Belts. There appears to be no common relation between temporal changes of temperature and changes in the visual albedo of the various axisymmetric bands.

Subsuns, Bottlinger's rings, and elliptical halos.

Subsuns, Bottlinger's rings, and elliptical halos are simulated by the use of a Monte Carlo model; reflection of sunlight from almost horizontal ice crystals is assumed. Subsuns are circular or elliptical spots seen at the specular reflection point when one flies over cirrus or cirrostratus clouds. Bottlinger's rings are rare, almost elliptical rings centered about the subsun. Elliptical halos are small rings of light centered around the Sun or the Moon that rarely occur with other halo phenomena. Subsuns and Bottlinger's rings can be explained by reflection from a single crystal, whereas elliptical halos require reflection from two separate crystals. All three phenomena are colorless and vertically elongated with an eccentricity that increases with increasing solar zenith angle. For several cases of Bottlinger's rings the simulations are compared with density scans of photographs. Clouds that consist of large swinging or gyrating plates and dendritic crystals, which form near -15 °C, seem the most likely ca didates to produce the rings and elliptical halos. Meteorological evidence is presented that supports these conditions for elliptical halos. Simulations suggest that the most distinct elliptical halos may be produced by hybrid clouds that contain both horizontal and gyrating crystals.

Rainbows and fogbows.

The optics of rainbows and fogbows is investigated theoretically for monodisperse drops using Mie theory. Included in the calculations are a realistic solar illumination spectrum and the finite size of the sun. Drop sizes range from 3 to 300 microm (3800 > X > 38). Results are presented on the location, width, contrast, polarization, and color of both primary and secondary rainbows. Particular attention is given to rainbows formed in small drops (fogbows).

Step brightness changes of distant mountain ridges and their perception.

When successive ridges of distant mountains are seen, observers often report that, near the ridge where the brightness changes abruptly, the upper part of the nearer ridge appears darker than at its lower portions. Similarly, they report that the base of the more distant mountain seems brighter adjacent to the nearer ridge than on its upper portions. The explanation of this phenomenon, known as the step contrast effect, is a special case of Mach bands. It is usually attributed to a visual illusion involving lateral inhibition in the eye, which is most apparent in the vicinity of step brightness changes. Using analytic techniques and numerical integrations to simulate the airlight-induced brightness distributions of such scenes, we show that in many cases the perceived brightness distribution is qualitatively similar to the true brightness distribution and thus is not a visual illusion.

Ulloa's observations of the glory, fogbow, and an unidentified phenomenon.

Ulloa's complete print of the glories and fogbows on Mt. Pambamarca in Peru (now Ecuador) is presented. It shows two other phenomena, an erupting volcano and an as yet unidentified optical effect. The glories and fogbow are analyzed to obtain the drop size of the fog, and the unidentified features are discussed.

Mountain shadow phenomena. 2: The spike seen by an off-summit observer.

The oblique spike or contrast edge seen by an off-summit observer on a mountain shadow when the sun is low is shown to be a perspective effect that depends on the observer's position within the shadow. The degree of visibility of the shadow is due to contrast effects between differently illuminated aerosols. Numerical simulations are used to demonstrate these points.