title: Specific mRNP complexes. Characterization of the proteins bound to histone H4 mRNAs isolated from L6 myoblasts.
abstract: These studies were designed to identify the proteins associated with specific mRNAs. L6 myoblasts contain a unique poly(A)-rich H4 mRNA as well as poly(A)-minus H4 mRNA subspecies. We have characterized the proteins present in both poly(A)-rich and poly(A)-minus histone H4 mRNP complexes following ultraviolet cross-linking in vivo. In addition, the muscle-specific myosin heavy chain (MHC) mRNP complex was characterized in myoblasts. [35S]Methionine-labelled poly(A)-rich and poly(A)-minus RNP complexes were prepared from both the polysomal and free (post-polysomal) RNP compartments. From each fraction the mRNP encoding histone H4 or MHC was purified by hybrid selection to a cloned human histone H4 gene or MHC cDNA. A unique set of 6-16 proteins was found bound to each of the specific mRNP complexes. These proteins were a subset of the total population of either polysomal or free RNP proteins and some proteins appeared common among the different hybrid-selected RNP fractions. The results demonstrate that (a) mRNAs bind a different set of proteins depending upon whether they are present in the polysomal or free mRNP fraction; (b) the presence of poly(A) sequences affects the proteins which bind to H4 mRNA in the free RNP compartment.
authors.forename: S D
authors.initials: SD
authors.lastname: Ruzdijic
authors.forename: R C
authors.initials: RC
authors.lastname: Bird
authors.forename: F A
authors.initials: FA
authors.lastname: Jacobs
authors.forename: B H
authors.initials: BH
authors.lastname: Sells
mesh_terms: D000818:Animals; D002460:Cell Line; D002500:Centrifugation, Isopycnic; D003001:Cloning, Molecular; D004247:DNA / Q000032:analysis; D006657:Histones / Q000302:isolation & purification*; D006801:Humans; D009124:Muscle Proteins / Q000302:isolation & purification*; D009132:Muscles / Q000032:analysis*; D009218:Myosins / Q000302:isolation & purification; D009693:Nucleic Acid Hybridization; D011061:Poly A / Q000302:isolation & purification; D011132:Polyribosomes / Q000032:analysis; D012333:RNA, Messenger / Q000302:isolation & purification; D051381:Rats; D012261:Ribonucleoproteins / Q000302:isolation & purification*
chemical_list: D006657:Histones; D009124:Muscle Proteins; D012333:RNA, Messenger; D012261:Ribonucleoproteins; C026452:messenger ribonucleoprotein; D011061:Poly A; D004247:DNA; D009218:Myosins