Interphase Nucleus Flashcards
Nuclear Envelope Structure
Double membrane which is continuous with endoplasmic reticulum divided into segments limited by nuclear pores
Components of Nuclear Membrane
Outer: Ribosomes
Inner: Integral proteins for binding to nuclear lamina which attaches to marginal heterochromatin
Nuclear Pore Complex
10 nm, regulates passage of proteins into and proteins and RNA out of nucleus, max protein size is 40 kD
Pore Complex Structure
3 Octameric Rings of proteins including nucleoporins which bind to nuclear localization sequence receptor protein
Nuclear Cargo Proteins
Protein with NLS which is a zipcode of basic amino acids
NLS-Receptor Proteins
Bind to nuclear protein cargo and escorts them to nuclear pore (i.e. Importin)
Exportins
Proteins with Nuclear Export Sequences to leave the nucleus
Active Nuclear Import and Export
High Ran-GTP in nucleus to cytosol, binds to empty nuclear import receptors and cargo-bound export receptors to take them to cytoplasm
Nuclear Lamina Structure
Bound to inner nuclear envelope made up of lamin A, B, and C
Lamin B attaches via Lamin B Receptor
Lamin A&C interact with marginal heterochromatin
Function of Nuclear Lamina
Interphase: Keeps spherical structure of nucleus
Mitosis: Hyper-phosphorylation of A and C to dissolve, while Lamin B is preserved
Diseases from Mutation of LMNA
Muscular dystrophy
Cariomyopathy
Premature Aging
Structure of Nucleolus
Membraneless 10 chromosome pieces containing rRNA come together
Internal Nuclear Matrix Role
Many non-histone proteins, provides non-random order of chromatin
Evidence for non-random order of chromatin
Tissue-specificity, chromosomes occupy specific positions, and DNA replication and transcription occur in nuclear matrix
Rabl Configuration
Idea that chromosomes are non-randomly situated, using laser microradiation in 1980s, he was shown to be correct
