The 68 kDa protein of signal recognition particle contains a glycine-rich region also found in certain RNA-binding proteins.

Signal recognition particle (SRP) interacts with the signal sequence in nascent secretory and membrane proteins and directs them to the membrane of the endoplasmic reticulum. Membrane targeting is mediated by the 68 and the 72 kDa proteins of SRP. We have cloned and sequenced cDNA encoding the 68 kDa protein of canine signal recognition particle (SRP68). SRP68 is a basic protein comprised of 622 amino acid residues. Close to the amino terminus there is a glycine-rich region which SRP68 has in common with some RNA-binding proteins. SRP68 shares no detectable similarity to any of the proteins in data libraries.     

Dynorphin-Related Opioid Peptides in the Neurointermediate Pituitary of Rats Are Not α-N-Acetylated

Immunoreactive dynorphin in the neurointermediate pituitary of rats was found to consist of four different molecular weight forms. The three larger molecular weight forms, with apparent molecular weights of 4800, 3200, and 1700, constituted more than 80% of the total dynorphin immunoreactivity, and each liberated leucine-enkephalin but not alpha-N-acetyl-leucine-enkephalin upon enzymatic treatment with trypsin followed by carboxypeptidase B. Only a minor portion of the smallest dynorphin-related molecular weight form, dynorphin-(1-8), released alpha-N-acetyl-leucine-enkephalin upon enzymatic cleavage. This suggests that the vast majority of dynorphin-related peptides in the rat neurointermediate pituitary is not alpha-N-acetylated. The exceptionally high opiate-like activity of the molecular weight 1700 dynorphin suggests that this dynorphin-related opioid peptide may constitute the major part of opioid activity in the neurointermediate pituitary of rats.     

Lesions of the hypothalamic arcuate nucleus produce a temporary hyperalgesia and attenuate stress-evoked analgesia

In an attempt to elucidate the role of β-endorphin in the modulation of ‘basal’ nociceptive threshold and in the mediation of the antinociception (analgesia) evoked by stress, a series of lesions of the arcuate nucleus, the origin of the central system of β-endorphinergic neurones, were performed. These lesions produced an ～80% depression in the level of β-endorphin immunoreactivity in both the hypothalamus and periventricular β-endorphinergic fibre-containing tissue. A 50% decrease in the neurointermediate lobe content of immunoreactivity, but no change in the levels of this in the anterior lobe was also observed. Arcuate lesioned rats were significantly hyperalgesic in comparison to sham animals on day 4 post-operation, but on days 10 and 12, the basal nociceptive threshold of lesioned and sham groups did not differ significantly. On day 12 post-surgery upon exposure to 5 min foot-shock stress, lesioned rats developed a significantly smaller increase in tail-flick latency than did sham animals. These data are evidential of the importance of the arcuate nucleus in the determination of basal nociceptive threshold and in the generation of the analgesia which accompanies stress and are, further, suggestive of a role of central β-endorphin in the mediation of these processes.     

LDL receptor-related protein internalizes and degrades uPA-PAI-1 complexes and is essential for embryo implantation.

The low density lipoprotein receptor-related protein (LRP) is a large multifunctional clearance receptor that has been implicated in the hepatic uptake of chylomicron remnants and in the removal of protease-inhibitor complexes from the circulation and from the extracellular space. Disruption of the LRP gene in mice blocks development of LRP-/- embryos around the implantation stage. The expression pattern of LRP in the postimplantation stage embryo is identical to that of urokinase, a plasminogen activator that confers invasive properties to migrating cells. We demonstrate that LRP mediates uptake and degradation of urokinase-type plasminogen activator-plasminogen activator inhibitor 1 complexes and propose that the inability of the giant cells to remove the inactive protease complexes from their surfaces interferes with implantation of the embryo.     

Cell cycle-dependent reactivity with the monoclonal antibody Ki-67 during myeloid cell differentiation

The specificity and sensitivity of the monoclonal antibody Ki-67 in identifying proliferating cell compartments was tested with the human promyelocytic leukemia cell line HL-60 using multi-parameter flow cytometry. While correlated measurements of DNA content and Ki-67 immunofluorescence indicated that the antigen was present in all phases of the cell cycle, reactivity with the antibody was highest in proliferating S and G2+M cells. The analysis of the BrdU content of cells sorted on the basis of reactivity with Ki-67 showed a correlation between Ki-67 reactivity and BrdU uptake. In HL-60 cells induced to differentiate with dimethyl sulfoxide (DMSO), the loss of reactivity with Ki-67 paralleled the exit of cells from the cell cycle. This was not observed in DMSO-resistant HL-60 cells. These results validate the usefulness of the Ki-67 antibody for determining the proliferative stage of mammalian cells in culture.     

Involvement of endorphins in emotional hyperthermia of rats

When rats were confronted with the novel experience of a new environment and stressful handling procedure their body temperature increased within minutes. At the same time β-endorphin-like immunoreactivity in the plasma increased dramatically. The stress-induced hyperthermia could be antagonized or reversed by the active, not however, by the inactive enantiomer of naloxone. The data provide evidence for a physiological role of endorphins.     

The fine structure of exfoliated cervical and vaginal cells.

In order to understand the means by which cellular aggregates were maintained in gynecologic samples, the fine structure of samples derived from a number of women of various ages was examined with special attention paid to the intercellular junctions. Most cells in the samples were squamous cells containing numerous intercellular fibrils and glycogen granules. Parabasal or intermediate cells were also seen as well as occasional endocervical cells. All of these cell types were often found as parts of aggregates and, while other cell junctions were present, desmosomes were the most prominent. It was concluded that desmosomes were probably responsible for maintaining the aggregated state of many of the cells found in gynecologic samples.