Evidence of a precursor form of stratum corneum basic protein in rat epidermis

Abstract

The fully differentiated anucleate cells of the stratum corneum of newborn rat epidermis contain a cationic protein called stratum corneum basic protein (SCBP). This protein has a molecular weight (49 000) and an amino acid composition similar to a protein extracted from the less differentiated cell layers of the epidermis. Pulse--chase experiments with radiolabeled histidine were undertaken to test the possiblity that SCBP is derived from a preexisting protein. A protein of 52 000 daltons is rapidly but transiently labeled in extracts of the less differentiated cell layers. As the amount of label in the 52 000-dalton protein decreases, an increase in radiolabel is observed in extracts of the fully differentiated cells. This label is found in SCBP, a protein of lower molecular weight (49 000) than that initially labeled. These proteins are immunologically related and both are resistant to cyanogen bromide cleavage. They differ in apparent molecular weight on sodium dodecyl sulfate--polyacrylamide gels and in their net charge. The results are consistent with the conversion of a precursor protein into SCBP.

Biologic Structure and Function: Perspectives on Morphologic Approaches to the Study of the Granular Layer Keratinocyte.

“…In concert with these observations were the biochemical data which revealed that histidine-rich, basic protein in the keratohyalin granule was a high molecule weight, phosphorylated, polymeric precursor (now called profilaggin [45]) of the immunologically cross-reactive protein in the stratum corneum cell [46][47],…”

Identification of a Rapidly Labelled 350K Histidine-Rich Protein in Neonatal Mouse Epidermis

“…Ball et al [l] found that the granular cell HRP (HRPJ extracted in a heterogeneous molecular weight form (between 60-1,OOO K) and suggested that it was a polymer of various numbers of subunits of an earlier precursor (HRP,). Dale and Ling [9] and Lonsdale-Eccles et al [15], on the other hand, isolated granular cell HRP in the form of a stable 53 K phosphoprotein, although this had a strong tendency to polymerise. In contrast, it has been shown [21] that a single phosphorylated polypeptide of very high molecular weight accounts for the majority of the granular cell HRP in neonatal rat and adult guinea pig epidermis, under extraction conditions which minimise protein degradation.…”

Cyclic Amp‐dependent Protein Phosphorylation of Pig Epidermal Homogenates

“…Acrylamide gels (7.5%) were prepared before use as described by Fairbanks et al (18) with slight modification (concentration of 50S, 0.1 %). The four major bands in epidermal homogenates were identical to those of fibrous keratin proteins extracted by the method of Dale et al (19) as described previously (20,21). The gels were dried on Whatman No.…”